A dry but rather dull month

Mild and dry might not be the first thing you think of looking back at November as we have seen the first significant frosts of the season in England and Wales, but the month for the UK as a whole has had its sixth warmest November (for Mean Temperature) in a series that goes back to 1884.

The east and north-east coast of England has experienced relatively dry conditions over the month having only seen half of its average rainfall for the month. Tyne and Wear has had its driest November in 60 years, receiving only 24% (16.7mm) of its monthly average rainfall. The driest November on record for Tyne and Wear was in 1958 seeing 14.2mm of rainfall. This November is now the second driest November on record for Tyne and Wear, which was also the driest area in the UK.

Tim Legg, a scientist in the National Climate Information Centre, said: “For the UK as a whole it was a rather dry, but also rather dull month. The dryness in eastern counties, most especially Tyne and Wear, has been due to the prevalence of westerly winds during November, and these dry areas are to the lee of the Pennines. The westerly or south-westerly winds are generally moist, but most of the moisture comes out as rain over windward-facing hills – especially the Lake District and Pennines – and hence the air is relatively dry as it descends towards the east coast.  Also at play to some extent is the Foehn or “Föhn” effect, where the drier air warms as it descends.”

The start of November saw a continuation of the very unsettled spell with which October had concluded, with significant rain in many areas. Things then settled down with a cold snap between 4th and 6th, bringing the first notable frosts for much of England and Wales. It soon became milder again with low-pressure systems being held to the west as pressure was higher over the Continent. Towards mid-month it became more widely unsettled again, with some heavier falls of rain in places but remaining very mild.  

Rainfall

East and north-east England was the driest district, receiving only 51% (39.7mm) of its rainfall, Tyne and Wear recording the lowest in the area making it their second driest November on record. Surrounding areas in east and north-east England also received much lower than average rainfall totals, including Durham at 55% (50.2mm), Northumberland 49% (46.1mm), and Lincolnshire 39% (22.7mm).

In contrast, Northern Ireland has been the only region to exceed its average monthly rainfall with 106% (119.1mm), and County Fermanagh recording 129% (154.3mm).

Lower than average rainfall is a theme for November with many other areas across the UK also being much drier, including: Aberdeenshire 42% (47.3mm), Angus 52% (59.6mm), Banffshire 44% (49.1mm), Bedfordshire 58% (34.6mm), Berwickshire 47% (37.5mm), Caithness 49% (57.9mm), Cambridgeshire 52% (27.9mm), City of Aberdeen 29% (26.5), East Riding of Yorkshire 37% (23.2mm),  Kincardineshire 44% (45.7mm), Leicestershire 56% (34.1mm), Moray 48% (39mm), Norfolk 57% (37.8mm), Nottinghamshire 47% (26.6mm) and South Yorkshire 48% (34.7mm).

The counties with the most rainfall relative to the monthly average were: Argyll and Bute 126% (283.3mm), Ayrshire and Arran 112% (182.2mm), Cumbria 114% (176.9mm), Dunbartonshire 116% (226.3mm), Lanarkshire 111% (142.6mm), Renfrewshire 114% (193.6mm), Stirling and Falkirk 118% (239.2mm) and Western Isles 110% (190.3mm).

Rainfall
Provisional November figuresActual rainfall% of the November average   
UK100.9mm84
England62.2mm71
Wales131.9mm81
Scotland153.8mm93
Northern Ireland119.1mm106

Sunshine

Sunshine for most this month has been below or close to the monthly average, but south-west Scotland and Northern Ireland were the dullest areas (western Scotland 69%, 34.6 hours and Northern Ireland 74%, 39.7 hours). The only districts to reach 100% of the monthly sunshine hours were northern Scotland 110% (38.1 hours) and East Anglia 107% (72.6 hours).

Individual counties that experienced a rather dull month were Ayrshire and Arran with 57% (29.8 hours) of their monthly average, City of Glasgow 56% (31.2 hours), Dunbartonshire 59% (30.6 hours), and Renfrewshire 54% (29.8 hours).

Sunshine
Provisional November figuresActual sunshine in hours% of the November average   
UK53.193
England60.994
Wales54.597
Scotland42.192
Northern Ireland39.774

Temperature

Temperatures for the UK were around 1.5°C above average in November, which has contributed to the autumn season finishing around half a degree warmer than average. The warmest county relative to average was East Sussex with a mean temperature anomaly of +2.1 °C above average. Tyne and Wear was not far behind with a mean temperature of +1.9°C above average for the month.

Maximum temperature  Minimum temperature
Provisional November figuresActual °CDifference from Nov average °CActual °CDifference from Nov average °C 
UK10.71.54.81.5 
England11.51.65.31.5 
Wales11.01.45.01.1 
Scotland9.31.63.91.7 
Northern Ireland10.41.04.91.4 

You can get the most accurate and up to date forecast for your area using our forecast pages and by following us on Twitter and Facebook, as well as using our mobile app which is available for iPhone from the App store and for Android from the Google Play store. You can check the latest weather warnings on our severe weather warnings pages. 

For the latest guidance to follow during the COVID-19 pandemic please visit the UK Government’s coronavirus advice page. Those living in Scotland, Wales and Northern Ireland can access country-specific advice. 

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Tropical Deforestation – a log jam on the road to Net Zero?

With one year to go until COP26 in Glasgow, and today’s launch of Together For Our Planet, Met Office Chief Scientist Professor Stephen Belcher reviews the influence tropical deforestation is having on the journey to a resilient Net Zero through the significant role they play in balancing atmospheric CO2 concentrations, storing carbon and changing the water cycle.  

We all learn about the basic principles of photosynthesis at school, the importance of plants providing the oxygen we breathe and also how they absorb carbon dioxide. So, on a simple level we all understand how important the ‘lungs’ of the earth are to enable all forms of life. But plants are also playing an important role in global climate change and the challenge to keep warming to manageable levels.  

Tropical forests cover a remarkable area, something like 12% (17 million km2) of the earth’s land surface. With this scale they not only cycle vast amounts of the oxygen that supports life, but are also incredibly important sinks of carbon from our atmosphere. Around 200 gigatons of carbon are stored in tropical forest vegetation, with further carbon stored in soils. If the carbon in the standing timber were released it would be equivalent to emitting 667 gigatons of CO2, which is equivalent to all fossil emissions of CO2 since about 1997. And as atmospheric CO2 concentrations increase as a consequence of human activity, tropical forests are likely to act as stronger sinks for carbon.  

So, deforestation reduces the amount of carbon that forests can store, meaning that a higher proportion of future CO2 emissions from fossil fuels will remain in the atmosphere, leading to larger changes in climate. And deforestation is a double whammy: by cutting down these trees we also release CO2 emissions previously stored in the forest system. 

Deforestation also affects the climate by altering surface distribution of radiation, water and heat, so-called non-CO2 effects.

Tropical forest is often replaced by crops and pasture, which tend to be lighter in colour than forests, which means that after deforestation more sunlight is reflected from the land back into space. This reduced absorption of sunlight leads to cooling.  

However, when plants take in CO2 from the air they transpire, they lose water to the air, which carries heat away from the surface. Crops and grasses tend to transpire less than forests, meaning that after deforestation heat is less efficiently lost from the land surface and the surface climate is warmer. 

The numbers are delicate. At high latitudes deforestation causes a large cooling effect from increased reflection of sunlight and a small warming from reduced transpiration, resulting in a net cooling at the surface. However, in the tropics, where deforestation rates are currently highest, the transpiration affect is much larger, and deforestation causes a net warming at the surface. 

Although not as important on a global scale, these non-CO2 effects are one of the most important contributors to warming near the location of deforestation. This effect does have global implications because warmer local temperatures reduces the ability of the forest to absorb atmospheric CO2 by photosynthesis, leading to a warmer background global climate.  

There is also moisture recycling and land management to consider. For example, different crops can have varying responses to factors such as drought, and ploughing releases further CO2 emissions from the soil, reducing the carbon sink still further. Deforestation can also impact the rainfall in other parts of the forest, meaning they may not get the rainfall they need to stay healthy and resilient. It may even affect rainfall patterns elsewhere in the world.

It’s important to understand the scale. Statistics from the UN’s Food and Agriculture Organization (FAO) show that, at its peak, the rate of deforestation in the tropics reached 95,430 km2 per year. This has gradually decreased from 1990 to 2015, dropping to 55,200 km2 per year. But that is still around a football pitch every 4 seconds for the 2010-2015 period, or all of the forests in the UK gone in about 7 months! Concerningly deforestation of the Amazon has increased, particularly in 2019 which saw the highest rate in a decade.  

So what does this all mean in the context of net zero, the target that nations around the world are racing towards to balance up their carbon emissions and not contribute further to human induced climate change?  

Well, its first important to say that net zero will not be achieved through limiting tropical deforestation alone. Ultimately net zero can only be achieved by substantially reducing the use of fossil fuels. However, net zero will be made easier if tropical deforestation is limited.

While net zero is an important target, it is not only climate change that will benefit from stopping deforestation. Forests are important habitats, are culturally important and provide other ecosystem services. So there are a multitude of benefits from taking the same action.  

Positive steps are being taken. For example, Brazil’s stated Intended Nationally Determined Contribution (INDC) to the UN’s climate change treaty includes eliminating illegal logging and restoring 120,000 km2 of forest by 2030. 

So what can science do to play a part? We need to quantify the effects of deforestation on climate, and work at the Met Office is doing just that. We have developed with UK academic partners the UK Earth System Model (UKESM1) to simulate two-way feedbacks between forests and climate, including the impacts of deforestation and the impact of climate change on forest resilience.  

Alongside this large-scale perspective, we are also working to better understand the small-scale processes that drive the processes, using the JULES land-surface model to simulate forests at key observational sites. Much of this work is being done under the CSSP Brazil program in partnership with Brazilian colleagues at INPE, INPA and CEMADEN, and with UK academic partners. 

Ultimately, we are using our earth system modelling to assess the impacts of future deforestation and mitigation on climate and to calculate carbon budgets that avoid the worst impacts of climate change. With this scientific information policy makers can make informed decisions on how they will act when it comes to deforestation.  

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A record-breaking year for Atlantic Tropical Storms

2020 is shaping up to be a year for weather records – a new record for the highest temperature reliably recorded on earth in Death Valley this summer, the most land scorched in a single year during the Californian wildfires and now the busiest season on record for Atlantic tropical storms. 

Julian Heming, Tropical Prediction Scientist at the Met Office said: “With the naming of Tropical Storm Theta earlier this week, the count for tropical storms in the Atlantic this season currently stands at 29, surpassing the previous record busiest year of 2005.   

“Indicating just how busy this year’s Atlantic hurricane season has been, forecasters were forced to use supplementary names from the Greek alphabet, after using up all names on the official National Hurricane Center list for 2020.  This has only ever happened once before in 2005.” 

This year’s Atlantic hurricane season has also set a new record for the most consecutive years where the season started early. The season officially starts on 1st June, but this year Tropical Storms Arthur and Bertha formed off the east coast of the USA in May, marking the sixth year in a row where the hurricane season started before the official start date. 

Commenting on the record-breaking year, Julian Heming continued: “From early in the season there were higher-than-average sea surface temperatures across much of the region and low vertical wind shear which allows storms to form more readily. 

“The latter condition is partially as a result of the La Niña which has now become established. In addition to the early start to the season, the latter part of the season (October and November) has been exceptionally active, which has helped drive the storm count to record levels.” 

There are currently indications that another storm could develop in the Caribbean Sea, so extending the record storm count. Whilst the season ends officially on 30 November, activity can continue beyond this date – particularly in active seasons. For example, in the previous record setting season of 2005 there were two storms in December.

You can get updates on the latest tropical cyclones by following @metofficestorms

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UK sees fifth wettest October since 1862

One thing for certain is that October 2020 will be remembered for being exceptionally wet for some areas of the UK. The unsettled weather following Storm Alex brought enough rain on 3rd October to make it the wettest day on record for UK-averaged rainfall (31.7 mm, beating the previous wettest day of 29.9 mm on 25th August 1986). Persistent rain between the 2nd and 4th across the whole UK led to many stations breaking records for daily rainfall totals, and many parts of England and eastern Scotland have largely exceeded their average rainfall for October, making October 2020 now rank as the 5th wettest October on record for the UK. 

The month finished as it began as two separate Atlantic low-pressure systems brought further heavy and persistent rain as well as strong south-westerly winds. Yellow warnings covered parts of north-west England, Wales and western parts of Scotland. The remnants of former hurricane Zeta brought strong winds to the UK, and a weather station in Sutherland recorded the strongest gusts in the month of 79mph on the 31st.  

Towards the end of the month a warm conveyor – a band of warm, moist air that gets carried aloft in a frontal weather system and leads to the formation of heavy and persistent rain – brought continual rain on a south-westerly flow to parts of the UK, especially high ground in the west, including Brecon Beacons, Snowdonia National Park and the Lake District. The forecasting of this feature led the Met Office to issue yellow warnings for heavy rain. 

Rainfall  

Tim Legg, a scientist from the Met Office National Climate Information Centre, commented: “Rainfall totals were near average in many western areas of the UK but well above average in some eastern areas including eastern Scotland, north-east England, the south Midlands, London and central southern England. Overall, the south-east of England has experienced the highest volume of rainfall with 188% (174.3 mm) of its monthly average and parts of London, south-east England and Aberdeenshire had double the average rainfall.” 

On a county level Oxfordshire experienced the highest volume of rainfall with 222% (160.5mm) of their monthly average. Closely followed by Greater London with 217% (158.1mm) of their monthly average. This month’s provisional figures show that this October for Greater London is the eighth wettest calendar month (in a series that starts in 1862), the fourth wettest October over the same period, and the wettest October in 20 years. November 1940 still holds the record for the wettest month in Greater London with 171.2mm of rainfall. 

The October rainfall in Moray, north-east Scotland, was greater than any October since records began in 1862. The area received 205% (200.6mm) of its average October rainfall, following low-pressure systems which were influenced by the decaying elements of Ex-Hurricanes Zeta and Epsilon. A weather station in Kinloss, Moray recorded 165.4mm of rain in the month, 232% of its average rainfall.  

Other regions that exceeded double their monthly average rainfall are Bedfordshire 204% (132.7mm), Berkshire 215% (168.1mm), Buckinghamshire 214% (159mm), Essex 211% (134mm), Hertfordshire 217% (159.2mm), Hampshire 205% (203.6mm), and Kincardineshire 211% (237.5mm).  

Durris, Kincardineshire received 112.4mm of rainfall in just one day on 3rd October (its wettest day on record), beating the previous record of 90.3mm on 21st October 2009. 

 Rainfall 
Provisional October figures Actual rainfall % of the October average    
UK 179.3mm 142 
England 140.6mm 154 
Wales 208.4mm 123 
Scotland 238.1mm 136 
Northern Ireland 165.7mm 139 

Temperature 

There has been an absence of warm days this month, with daytime temperatures mostly a little below average. There was a period of warmer moist tropical maritime air around the 20th and 21st, with a maximum temperature of 19 Celsius being recorded on the 20th at Kew Gardens in Greater London. Overall, temperatures have been mostly near or slightly below average, with daytime temperatures particularly suppressed relative to the seasonal average.  

The lowest minimum temperature recorded was –3.3 Celsius at Tyndrum, Perthshire in Scotland on the 15th and the highest temperature recorded was 19.1 Celsius at Writtle, Essex on the 8th.    

 Maximum temperature  Minimum temperature  
Provisional October Actual °C Difference from Oct average °C Actual °C Difference from Oct average °C 
figures     
UK 12.4 -0.4 6.4 0.2 
England 13.4 -0.5 7.2 0.3 
Wales 12.5 -0.6 6.9 0.2 
Scotland 10.7 -0.2 5.1 0.1 
Northern Ireland 12.4 -0.3 6.2 0.1 

Tim Legg said, “Gardeners would have expected to see at least one air frost in southern England in October, but the only recorded frosts this October were confined to northern regions.” 

Sunshine 

October for the UK as a whole was rather dull, seeing less than three-quarters of its average sunshine hours (72%). For the South of England in particular only 62% of the average sunshine was recorded. Northern Ireland has seen the most sunshine with 101% of its average for the month, with County Armagh receiving 108% (99.7 hours).  

Tim Legg in the Met Office National Climate Information Centre says, “Sunshine was well below average generally, most especially in East Anglia, but near average in Northern Ireland and the Isle of Man. For the UK as a whole this was the fifth wettest and also the fifth dullest October in the historical series, since 1862 and 1919 respectively”.  

 Sunshine Hours 
Provisional October figures Actual sunshine in hours % of the September average    
UK 66.0 72 
England 67.4 65 
Wales 62.9 68 
Scotland 60.2 80 
Northern Ireland 88.5 101 

You can get the most accurate and up to date forecast for your area using our forecast pages and by following us on Twitter and Facebook, as well as using our mobile app which is available for iPhone from the App store and for Android from the Google Play store. You can check the latest weather warnings on our severe weather warnings pages. 

For the latest guidance to follow during the COVID-19 pandemic please visit the UK Government’s coronavirus advice page. Those living in Scotland, Wales and Northern Ireland can access country-specific advice. 

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State of the African Climate update and the importance of climate services

Every year the World Metrological Organization (WMO) publishes a range of reports examining the latest evidence on different meteorological and climatological factors. This year, a group of international specialists has produced a report specifically focusing on the State of the Climate in Africa, providing a snapshot of climate trends, observed high-impact events and associated risks and impacts in key sensitive sectors.

The Met Office was part of this group with scientists providing information on observed temperatures and detail on projections of what we could see in Africa in the future.   

John Kennedy, who works on climate monitoring at the Met Office, was involved in the development of the report:

Africa is a hugely diverse continent, with vastly different landscapes ranging from rainforests to savannahs and deserts. As we are seeing in other parts of the world, temperatures in Africa have been rising in recent decades. 2019 was most likely the third warmest year on record for the continent, behind 2010 and 2016. As a continent, Africa was between 0.56°C and 0.63°C above its long-term average (1981-2010) temperature in 2019. Some individual countries including South Africa and Namibia saw 2019 temperatures locally exceeding 2°C above average.

As well as rising heat, Africa was affected by numerous extreme weather events in 2019, including Tropical Cyclone Idai, which was among the most de­structive tropical cyclones ever recorded in the southern hemisphere with over 1,200 associated deaths in Mozambique, Zimbabwe and Malawi.

Most areas of Africa, covering a wide range of climate zones, saw above average temperatures in 2019, but rainfall patterns were much more variable. In 2019, in Southern Africa severe drought affected many areas which had already suffered a prolonged drought from 2014 to 2016. Meanwhile, in the Greater Horn of Africa, conditions shifted from very dry in 2018 and the start of 2019 to floods and landslides associated with heavy rainfall in late 2019. Flooding also affected the Sahel and surrounding areas from May to October 2019.

WMO State of the Climate in Africa: Percentage of normal precipitation for October 2019 with respect to the 1951–2010 reference period, showing high precipitation across tropical Africa and low precipitation across the extra-tropics. Source: GPCC, Deutscher Wetterdienst, Germany.
WMO State of the Climate in Africa: Percentage of normal precipitation for October 2019 with respect to the 1951–2010 reference period, showing high precipitation across tropical Africa and low precipitation across the extra-tropics. Source: GPCC, Deutscher Wetterdienst, Germany.

While extreme events often depend on the chaotic whims of the weather, considered over longer periods – months, years, decades – we can discern patterns that allow us to understand and, in some cases, to predict them. While individual events can be forecast reliably only days in advance, long-term drivers can shift the odds of such events happening in a predictable way. The strong positive phase of the Indian Ocean Dipole was one such driver associated with the extreme rainfall in Eastern Africa late in 2019. As we look back over the past decades, the warming signal from increased greenhouse gases in the atmosphere is increasingly clear.

As climate change continues to influence our weather and climate extremes, to make sure we can make accurate projections for what sort of extremes we might see in the future it is vital to start any kind of research with an accurate foundation understanding of the area. To help with this, last year an international collaboration of scientists led by the Met Office developed the first convective-permitting regional climate model, known as CP4-Africa. This model enables scientists to look at much finer detail the kinds of rainfall extremes Africa could experience as our climate warms.

Lead author of the first paper on future climate change from the CP4-Africa simulations, Dr Elizabeth Kendon of the Met Office, explains that, “Very high resolution climate projections provide a glimpse into future weather and climate extremes over Africa. CP4-A suggests that over the Sahel and east Africa extreme heavy rainfall events that occur about once every 30 years now, may occur once every 3-4 years by the end of the century if emissions continue to rise throughout the 21st century under a high emissions scenario.

“Dry spells during the wet season exceeding 10 days in length are almost twice as frequent in the future compared to the present-day over parts of central and western Africa: a signal which is not seen in a coarser resolution 25km model.”

WMO State of the African Climate: Multi-model average forecasts of near surface temperature and precipitation for the five-year period 2020–2024. Colours show anomalies relative to the period 1981–2010 for the average of several international forecasts contributing to the WMO Lead Centre for ADCP (https://hadleyserver. metoffice.gov.uk/ wmolc/). Forecasts are initialised with observations and start on or after 1 November 2019. Source: Met Office, United Kingdom

It is well understood that Africa’s population and landscapes are vulnerable to extreme weather events. It is therefore important that we use our understanding to help those vulnerable communities prepare and adapt for future challenges as our climate changes.

Helen Bye is the Met Office’s Head of International Development and Principal Adviser to the Foreign, Commonwealth and Development Office (FCDO):

As detailed in the WMO 2019 State of the Climate in Africa report, Africa is vulnerable to the impacts of climate variability and change. Continuing to conduct climate research and improving climate modelling for the continent is vital to ensure the best possible understanding of the challenges ahead, in order to mitigate against and adapt to the impacts of climate change. This report also made reference to the need to strengthen multi-hazard early warning systems (MHEWS) and build capacity in the provision of climate services in Africa, and the WMO 2020 State of Climate Services report echoed this. According to the latest report, over the last 50 years 35% of deaths related to weather, climate and water extremes occurred in Africa and yet the continent has one of the weakest capacities in MHEWS.

At the Met Office we work with our global partnerships to help build capacity in weather and climate services, including in Africa. Those partnerships involve many and varied organisations, from the WMO, national and regional meteorological services, to non-governmental organisations, United Nations bodies and community initiatives. Critically our international development work takes a people-led approach, ensuring that the capacity building process is built around the needs of the users of weather and climate information.

The Risk-Informed Early Action Partnership, of which the Met Office is a founding member, contributed to the WMO 2020 State of Climate Services report and is an example of the global collaboration needed to bring about significant change. The partnership aims to make 1 billion people safer from weather and climate-related disasters by expanding early action financing and improving climate information and early warning systems and the capacity to act on the risks they identify.

One example of the benefits of MHEWS highlighted in the WMO 2020 State of Climate Services report (page 35) is on the Weather and Climate Information Services for Africa (WISER) HIGHWAY project, funded by the FCDO. Led by the WMO with partners including the Met Office, this project worked with the national meteorological services of countries bordering Lake Victoria to develop a regional Early Warning System (EWS). 3000 to 5000 deaths occur in the Lake Victoria Basin every year due to navigation accidents caused by strong winds and high waves also tragically resulting in loss of livelihood for their dependents. Data from the project suggests that there has been an approximately 30% reduction in deaths since the introduction of the EWS. You can learn more in this BBC World Service podcast (8:45-15:05).

The local challenges faced on Lake Victoria led to the development of this EWS, and the people-led approach I mentioned along with an understanding of the risk factors is key to improving or developing new weather and climate services in Africa. Different African countries and regions face different weather and climate challenges, so the weather and climate community and partners need to continue to translate robust science into relevant and timely services which enable people to take action to stay safe and thrive.

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Rainfall on UK’s wettest day on record could have more than filled Loch Ness

Saturday 3 October 2020 is now the wettest day on record since 1891 for UK-wide rainfall. It received the greatest rainfall in any single day averaged out across the UK, beating the previous record on the 25 August 1986.

UK rainfall map 3 October 2020

Saturday 3 October was the wettest day in the UK rainfall record stretching back to 1891.

Dr Mark McCarthy is the head of the Met Office National Climate Information Centre. He said: “In climate statistics, 2019 will be remembered for possessing the UK’s hottest day, whereas 2020 will be associated with rainfall records. Saturday 3 October – the day which followed Storm Alex – currently holds the record for the UK’s wettest day in a daily series stretching back to 1891 – that’s over 47,000 days. The rainfall was very widespread resulting in average rainfall across the entire UK of 31.7mm, or to put it another way, if expressed as the volume of rain that is more than the capacity of Loch Ness – the largest lake in the UK by volume at 7.4 cubic kilometres of water. It is exceptional to have 30 to 50mm or more of rain falling so extensively across the UK – from the south coast of England to the north coast of Scotland – in a single day”. The previous record was 29.8mm on 25 August 1986.

Loch Ness

At 7.4 cubic kilometres, Loch Ness is the largest lake in the United Kingdom by volume. Pic: Shutterstock.

 

 

Generally, the start to October (1-13th) has been very wet with the early provisional statistics showing the UK overall has seen 68% of its average rainfall for the month of October and England has been the wettest with 87% of its monthly average, in particular south east and central southern England already reaching 110%.

Commenting on 2020 Dr McCarthy added: “Remarkably, 2020 also has the UK’s third wettest day on 15th February with 27.2mm, from named storm Dennis during what then became the wettest February on record”.

More than 20 counties across the UK have already had 100% or more than their average October rainfall and many others are not far behind. Oxfordshire has been the wettest county compared to the 1981 – 2010 average with 148% average rainfall (107.1mm). Followed by Buckinghamshire reaching 139% (103.4mm) of its average rainfall, Berkshire with 138% (108.0mm) and Hertfordshire reaching 132% (96.9mm). Other counties already reaching 100% or above are Aberdeenshire, Angus, Banffshire, Bedfordshire, Berwickshire, Cheshire, City of London, City of Aberdeen, East Lothian, Essex, Gloucestershire, Greater London, Hampshire, Isle of Wight, Kincardineshire, Moray, Northamptonshire, Staffordshire, Surrey, Tyne and Wear, Warwickshire, Wiltshire and Worcestershire.

Wales, Scotland and Northern Ireland rainfall statistics remain at average numbers, and conversely Argyll and Bute has been significantly drier with only 29% of its average rainfall (70.7mm). The distribution of rainfall can be seen in the map below.

Average rainfall for October 2020

Already during October, many parts of the UK have recorded more than their monthly average rainfall for the month.

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Climate projections show extreme UK’s weather will become even more extreme

“The UK’s set of climate projections are the best window we have on how climate change is likely to affect us out to the end of the century,” said Professor Jason Lowe OBE*, the lead for UKCP – the UK’s climate projections.

The latest iteration of climate projections for the UK were released in 2018, updating the set from 2009. In the early days of climate projections, users were able to examine features such as the expected rise in average temperature for a given location at a particular time of year. “But users also need an understanding of what extremes of weather will be like: What will be the maximum temperature in summer? Or how much rain will fall in the heaviest rainfall events,” added Professor Lowe. Being able to interrogate the data in this way is exceedingly important for a whole range of user groups, from the rail industry to water companies and from town planners to the energy sector.

In 2019 there was a programme of additions , including a rollout of a new set of projections which examine climate extremes on a grid of 2.2km. This provides new capability to resolve the fine detail of weather extremes and predict events such as flash flooding, based on new capability to resolve the dynamics of thunderstorms.

In addition to more local detail, information is needed on uncertainties associated with future extremes, in order to support assessments of risks at the city-scale, for example. Later this week the Met Office will be releasing a further update which will add new probabilistic projections on the hottest and wettest weather extremes. Dr Simon Brown, who led this extension, explains: “This work provides a range of plausible outcomes for rare events expected on average once every 20, 50 and 100 years, for a range of emissions scenarios. This will allow planners to weigh the risk of different outcomes against the costs of adaptation.”

Exeter temperature extremes

One -in-twenty year temperature extremes for Exeter. Black line is the median value.

Ahead of the release of the data for the whole of the UK, the Met Office has released information for Exeter which shows the impact that climate change could be expected to have on the city.

Currently, in Exeter there is around a one-in-twenty chance of the city recording daily maximum temperatures exceeding 33.0 C, in a given summer. However the figures show that even with a mid-range scenario of greenhouse gas emissions (RCP4.5), this value would be more likely than not to exceed 35.0 C by 2090, while maximum temperatures of over 40.0 C cannot be completely ruled out.

The figures for rainfall extremes are also higher in the future than now. Currently, there is a likelihood that in one winter out of twenty the city will see a single day with over 45mm of rainfall, but by 2090 the same figure is nearly 50mm; around a 10 per cent increase of rainfall on the heaviest day for rain in winter. The projections show that values of around 60mm cannot be ruled out completely.

Professor Jason Lowe

Professor Jason Lowe OBE

More information about UKCP is available on the Met Office’s Weather Snap podcast.

 

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How will La Nina affect our winter weather?

La Niña is now present in the tropical Pacific and forecasters are suggesting these conditions will continue throughout the winter months.  

La Niña is one of the three phases of the phenomenon known as the El Niño-Southern Oscillation, El Niño – the warm phase, La Niña – the cool phase and lastly the neutral phase. During La Niña strong trade winds blow warm water towards the west Pacific causing an upwelling of cool water from the ocean depths in the east Pacific leading to variations in global weather. 

These changes in the location of warm and cool ocean water lead to a shift in rainfall towards the western Pacific putting areas such as north-east Australia, and Indonesia at risk of heavier than normal rainfall. While areas on the other side of the tropical Pacific, such as California, could be at risk of drought. La Niña can even influence the Atlantic jet stream and our weather here in the UK.  

Prof. Adam Scaife, head of long range prediction at the Met Office said, “La Niña has a profound effect on weather across the globe with us even seeing impacts that extend across the UK.  

“In late autumn and early winter it historically promotes high pressure in the mid-Atlantic, which stops Atlantic weather systems from delivering mild air to the UK, and therefore can allow cold conditions to intensify. However, in late winter La Niña can drive a shift of the jet stream towards the Poles increasing storminess and heavy rainfall, while bringing milder conditions”.  

Other factors affecting our winter weather.  

The Quasi-Biennial oscillation, the variation in winds high above the equator, is in its westerly phase at present and this increases the chance of a mild, wet and stormy winter. 

Meanwhile, the sun is in a new solar weather cycle, solar cycle 25. This cycle started around 9 months ago and at this stage can be associated with colder winter weather.  

How will La Niña impact global temperatures? 

Globally 2020 remains on track to be one of the warmest on record. Although La Niña historically reduces global temperatures, it is not expected to be enough to counterbalance human-induced climate change, but it may be enough to just prevent 2020 from being a new record. 

This comes after 2019 was one of the three hottest years on record and all the years since 2013 have been warmer than any previous years since records began in the 1800s. 

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Weather Statistics for September

Looking back at September as a whole it turned out to be a fairly average month, although there were a few notable events. For the first time in 4 years we saw temperatures reach 30 degrees and a few long running observing sites recorded their highest September temperature on record, although the end of the month saw more unsettled weather and cooler air, including a record low September temperature for Northern Ireland.

The first few days of September were rather unsettled, with frontal systems moving across from the west. Southern areas began to see less in the way of rain from the 9th onwards, whereas fronts continued to affect the north, with an especially wet period in western Scotland on the 12th/13th. Warm air moved into southern and eastern areas from the 14th, with a late-season hot spell bringing temperatures not far off 30°C on the 14th and peaking at 31.3°C on the 15th, and settled conditions continuing beyond that for another few days. However, around the 23rd the weather became more unsettled and decidedly cooler.

Rainfall

September rainfall was well below average for most regions of the UK, with only parts of western Scotland and East Anglia bucking this trend. Argyll and Bute received 203mm of rainfall, thanks mainly to heavy rain on the 12th while a slow-moving band of rain sat over much of the East Anglian coast on the 25th boosting rainfall levels here. Over the month Norfolk recorded 93.7mm of rain, 66% above its September average, with Houghton Hall receiving 45.2mm of rainfall on the 25th alone, while Cambridge weather station, around 55 miles inland, recorded no rainfall at all on that day.

Rainfall
Provisional September figuresActual rainfall% of the September average   
UK74.3mm77
England44.9mm65
Wales76.2mm65
Scotland121.8mm90
Northern Ireland58.1mm85

Temperature

For the first time since 2016 we saw temperatures reach 30 degrees in September. The 14th and 15th September were the warmest days this month. The 14th reached 29C and 6 weather stations recorded temperatures of 30C or above on the 15th.

Back in 2016 the hot weather was longer lasting and more wide-spread with temperatures reaching 34.4C at Gravesend in Kent on 13th September 2016.

Northern Ireland recorded its lowest minimum temperature on record for September on the 27th with a minimum of -3.7C. This beats the previous record of -3.6C which was again set at Katesbridge in 2018.

Maximum temperature  Minimum temperature 
Provisional September figuresActual °CDifference from Sept average °CActual °CDifference from Sept average °C
UK17.10.68.6-0.2
England18.60.79.3-0.2
Wales17.20.68.9-0.2
Scotland14.80.47.3-0.3
Northern Ireland16.50.48.6-0.1

Sunshine

September was a sunny month overall for many with most areas seeing above average sunshine hours.

Sunshine
Provisional September figuresActual sunshine in hours% of the September average   
UK145.3117
England166.2121
Wales153.7120
Scotland112.5107
Northern Ireland121.9107

You can get the most accurate and up to date forecast for your area using our forecast pages and by following us on Twitter and Facebook, as well as using our mobile app which is available for iPhone from the App store and for Android from the Google Play store. You can check the latest weather warnings on our severe weather warnings pages.

For the latest guidance to follow during the COVID-19 pandemic please visit the UK Government’s coronavirus advice page. Those living in ScotlandWales and Northern Ireland can access country-specific advice.

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Storm Alex, so why not Storm Aiden?

Many media outlets have been reporting that ‘Storm Aiden’ will batter Britain with strong winds and heavy rain this weekend. 

Over the last few days, weather forecasting computers – known as Numerical Weather Prediction (NWP) models – have been predicting a deep area of low pressure to develop close to the UK this weekend, bringing the potential for severe weather. Chief Meteorologists at the Met Office are closely monitoring developments.

Why do we name storms?

Since 2015 the Met Office, along with Met Éireann and KNMI, the national weather services in Ireland and the Netherlands, have been naming storms based on weather warnings in order to raise awareness of the potential impacts of severe weather.

Why do we name storms?

Latest NWP model output has moved the initial position of this weekend’s low-pressure system further south across France early on Friday. With very strong winds forecast, countries in the south-west Europe naming group – France, Spain, Portugal and Belgium – have named ‘Storm Alex’, which is the first name on their list for 2020-2021. The impacts further north were not considered strong enough for the Western European storm-naming group to name the system as ‘Storm Aiden’.

Later on Friday and over the weekend this system will move closer to the UK, bringing heavy rain and strong winds to many areas.

European Storm naming groups

When a storm is named by another weather service in Europe (see European storm naming groups image above) it is agreed that the same name will be used by all weather services in order to retain a consistent message.  Similarly, if a weather system impacting the UK were the remnants of a Hurricane that has moved across the Atlantic, we will use the same name, for example ex-Hurricane Ophelia in 2017.

This weekend, it will be wet and windy for many of us.  Keep an eye on the latest Met Office weather forecast and severe weather warnings where you are using our forecast pages and by following us on Twitter and Facebook, as well as using our mobile app.

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