Rain or shine this weekend?

20 08 2015

You may have heard that this weekend could be cloudy and wet…or sunny and dry, that’s because as with other weekends this summer there has been some uncertainty in the forecast.

After a mixed week of some sunshine, rain and showers it looks like we’ll see more of the same over the weekend as a frontal system interacts with warm, humid air spreading northwards from the continent.

We are now fairly confident that on Saturday the UK will be split weather wise. There’ll be bright and breezy weather in the north west with a few showers. Meanwhile the south east will be warm and humid, perhaps hot with temperatures in the high 20s which could set off a few isolated thunderstorms. In between we expect to see a band of cloud and rain which could be heavy and persistent at times.

Overnight and into Sunday the wet weather is expected to become more widespread across England and Wales and move into Scotland with some heavy rain at times.

Sun23Aug12z

At the moment, central and western parts of the UK seem most likely to see the heaviest, most persistent rainfall as the frontal system pivots. However, this pivot position could change over the coming days, and this is critical because it will determine whether we need to issue weather warnings.

Once we have more certainty where the most persistent, heavy rain will be we will review whether a Met Office National Severe Weather Warning is required. Therefore, as ever, it is best to check the latest forecast if you have plans for the weekend.

Tony Berry, Visitor Experience Director at the National Trust said: “Despite the unsettled weather this weekend, there’s still loads to do at National Trust places across the country. From windswept coastal paths and woodlands to hundreds of historic houses and gardens, there’s always something to explore come rain or shine. We’ve got a whole host of activities to wear the kids out too, with everything from pirate adventures and fossil hunts (just remember to pack the waterproofs and wellies) to storytelling and wild art. And throughout August we’ll be bringing the coast to a whole host of cities across the UK in the form of a giant shell – Shellsphere – where passers-by will have the opportunity to see, smell, hear and taste the sea.”

Next week, we’ll continue to see a combination of drier, sunny days with cloudier spells and some rain or showers at times but it will be warmer than recently.





Record hot to record cold in a July of extremes

3 08 2015

While this year’s July may not have broken any monthly records – it was book-ended with some localised daily records at both extremes of the temperature spectrum.

The month started with the highest recorded July temperature in our UK climate records with 36.7C recorded at Heathrow on 1 July.

Then on the last day of the month, we saw the opposite extreme – with a number of stations across the UK breaking their lowest recorded July temperature.

Some of these stations have fairly long records – below we’ve highlighted those stations which broke their July low record which have observations going back for 30 years or more.

STATION COUNTY PREVIOUS RECORD PREVIOUS RECORD DATE YEARS OF DATA TEMP 31/07/15
ALICE HOLT LODGE Surrey 3.9 03/07/1984 64 3.5
KEELE Staffordshire 5.2 16/07/2001 63 5
EXETER AIRPORT Devon 3.3 01/07/2011 50 2
CHIVENOR Devon 5.7 07/07/1996 38 5.6
PERSHORE Worcestershire 3 04/07/1965 36 2.7

These temperatures came about after several days of a northerly airflow which brought colder than average air over the UK. Clear skies allowed temperatures to drop rapidly overnight across many spots, leading to some of the localised records.

None of these new station records came close to breaking the all-time UK record for July of -2.5C which was set at both St Harmon (Powys) on 9 July 1986 and Lagganlia (Inverness-shire) on 15 July 1977. It’s worth noting here that lowest daily temperature records exclude stations above 500 metres above mean sea-level.

Other extremes for July 2015 are:

  • The wettest day was recorded at Cambridge Botanic Garden on the 16th, with 87.1mm of rain recorded in 24 hours. This is significantly more than the whole-month average for July at that station, which is 50.7mm.
  • The strongest gust was recorded at the Needles on the Isle of Wight on the 26th, with 60mph.
  • The Sunniest day was on Fair Isle, Shetland, on the 26th, with 16 hours of sunshine recorded.
  • The coldest temperature recorded during the month was a chilly -0.6C at Katesbridge in Down, Northern Ireland on 15 July – although this wasn’t a record for that station.
  • The warmest temperature was 36.7C recorded at Heathrow on 1 July – you can read more about that on our blog.




On the record – observing a ‘heatwave’

7 07 2015

Last week on 1 July the UK saw its warmest July daily max temperature on record (records date back as far as 1853), with 36.7 °C at Heathrow. This has led to considerable interest in the wider context of the record temperatures. Here, Mark McCarthy, Manager of the Met Office National Climate Information Centre discusses records and how we record them.

Where were record temperatures observed on 1 July 2015?

Although Heathrow measured the highest temperature recorded by the Met Office observing network on a July day, record temperatures were reported across a wide stretch of the country, including from some of the Met Office’s very long running climate stations.

Temperatures exceeded 35 °C at a handful of locations in London and the south east, but also reached the low 30s across the Midlands, East Anglia and parts of north-west and north-east England. It is in these areas that July temperature records were broken.

Map showing stations recording new July temperature records, 1 July 2015

Map showing stations recording new July temperature records, 1 July 2015

The table below lists those stations with more than 50 years of observations for which 1 July 2015 was a record. These data show that record temperatures for July were not confined to London or other major urban centres. The records were, in fact, part of a larger scale pattern of high temperatures extending through Spain, Portugal and France.

SITE DATE OF PREV JULY RECORD PREV RECORD JULY MAX (°C) 1 JULY 2015 MAX (°C) YEARS OF DATA
Durham 31/7/1943, 10/7/1921 30.6 31 133
Sheffield 31/7/1943, 10/7/1921 31.7 33.3 130
Bradford 31/7/1943, 13/7/1935 30.6 30.9 106
Cranwell 22/7/1996 32.6 34.3 93
Sutton Bonnington 19/7/2006 32.9 33.6 84
Stonyhurst 3/7/1976 31.1 32.6 75
Manston 15/7/1983 31.4 33.6 74
Goudhurst 3/7/1976 32.8 33.3 74
Waddington 12/7/1949 32.2 33.1 67
Heathrow 19/7/2006 35.5 36.7 66
Nottingham (Watnall) 3/7/1976 32.3 33.9 64
Marham 3/7/1976, 5/7/1959 32.8 33.5 58
Wittering 5/7/1959 32.8 35.3 53
St James’s Park 5/7/1959 34.4 34.7 52

How does this compare to past heatwaves?

Temperatures over 36 °C reported at any station in the UK observing network are very rare, with only a handful of notable heatwaves seeing such extremes. The heatwaves of August 1990, August 2003, and July 2006 each saw a number of stations exceed 36 °C, whereas on 1 July 2015 Heathrow was the only station.

The Met Office maintains a list of climate extremes for the UK. It is standard practice to report the highest and lowest temperature every month as part of our routine monitoring of UK weather and climate. It is therefore always noteworthy when one of these records is broken.

While there is no doubt that some previous heatwaves have seen more extreme or more widespread high temperatures overall – particularly in the climatologically warmer period from late July into early August – 1 July 2015 has the honour of holding the highest recorded temperature for a July day with 36.7 °C at Heathrow.

How do you ensure the data are reliable?

To ensure consistency, Met Office weather records are only given for stations with standard instruments and exposure. This means that our records would not represent the extremes that may have occurred in places where we do not have standard instruments. This may have been the case on 1 July 2015, where the availability of additional data from amateur observers contributing to Met Office WOW show peak temperatures in the range 35 to 37 °C to the west London.

It is reasonable to ask whether Heathrow, as a major international airport, can provide a reliable climatological record. Are the observations biased by the presence of runways and air traffic?

The instrumentation and station enclosure are managed so that they meet the standards required by the Met Office and set out by the World Meteorological Organization. The site has been operating for 66 years and provides an excellent long observational series for west London.

The first thing we can do is compare the climatological temperatures with a nearby station at Kew Gardens. The average daytime maximum temperatures for the two sites are very close:

Site June July August
Heathrow 21.04 °C 23.54 °C 23.15 °C
Kew 21.02 °C 23.48 °C 23.15 °C

On 1 July the maximum temperature recorded at Heathrow (36.7 °C) was higher than Kew (35.7 °C). Modern instrumentation means we can look at the temperatures minute-by-minute at the two sites, as shown below. The two locations recorded very similar temperatures through most of the afternoon and the average temperature at the two sites between 12:00 and 18:00 GMT agree to within 0.02 °C. However, there was a peak in temperature at Heathrow between 14:00 and 14:30 GMT that was not seen at Kew Gardens. What could cause such a peak?

Temperature (°C) graph for Heathrow and Kew Gardens 1 July 2015

There were scattered clouds in the area that afternoon. Both Heathrow and Kew Gardens have instruments measuring solar radiation, shown in the graph below. Both sites recorded a general dip in solar radiation due to clouds from approximately 13:30 to 15:00 GMT which corresponds to a slight cooling at both sites. Heathrow saw a short gap in the clouds shortly after 14:00 GMT which resulted in a similarly short lived peak in temperature, while Kew Gardens remained cloudy. In turn Kew Gardens then saw a brief spell being sunnier than Heathrow just before 15:00 GMT and became warmer than Heathrow for about an hour.

Solar radiation (W/m2) graph for Heathrow and Kew Gardens 1 July 2015





Hotter weather for the start of July

25 06 2015

The weather is showing signs of heating up next week for the start of the Wimbledon fortnight.

In contrast to June so far, which has seen temperatures often near or just below normal, next week could see a real change in the way it feels – with hot days and humid nights, especially across the south.

It looks like heat will start to build across Iberia later this weekend and spread northwards across France early next week as a tropical continental airmass begins to dominate the weather. Temperatures across Iberia and southern France could reach the low 40’s Celsius by midweek with northern France seeing temperatures into the mid to high 30s Celsius.

Data: European Centre for Medium Range Weather Forecasts

Data: European Centre for Medium Range Weather Forecasts

The UK is likely to be near the boundary between this tropical continental airmass and a tropical maritime airmass over the Atlantic, but we do expect to see temperatures rise across the whole of the UK for the start of July.

Scotland could see highs in the low to mid 20’s (although it may be cloudy here at times), and highs across southern Britain are likely to reach the low 30’s Celsius with a small chance of values in the mid 30’s here.

It’s worth saying that there is some uncertainty about how much of the hot weather from the continent will reach us, and it may only last a couple of days before temperatures drop a little. As is traditional with hot weather in the UK in the summer it may end with thunderstorms.





Record May temperatures for Spain

14 05 2015

Update: On Thursday, records were broken once again across southeast Spain. Valencia equalled Lanzarote Airport’s 42.6C from the previous day. Other stations in the Valenciana region exceeded this value, with Xativa and Carcaixent reaching 42.7C and 42.9C respectively; however these are as yet unconfirmed so are not official. Either way, not only is this 42.6C a new Spanish record for May, but a European-wide May record.  

Meanwhile, the heat is spreading to other parts of Europe, with extreme warmth expected today along the north coast of Sicily and parts of mainland southern Italy.

A new record maximum temperature for Spain was set yesterday, with many local records also broken, and the heat continues today in the southeast.

Iberia Temps

The new record of 42.6C was recorded at Lanzarote Airport in the Canary Islands, beating the previous May record for Spain by a relatively large 2.5 degrees. It also beats the Lanzarote station’s own previous highest May temperature by a whopping 6 degrees.

The previous May record in Spain was 40.1C at Cordoba on the mainland, and Cordoba itself recorded a new May station record on Wednesday with 41.2C.

Met Office Global Model mean sea level pressure and temperature

Met Office Global Model mean sea level pressure and temperature

Further records could be broken today in parts of Andalucía, Mercia and Valenciana as air continues to feed in from North Africa. However, a cold front is pushing gradually southeastwards across Spain, bringing cooler air across much of the country by the end of the week.





Possible record heat in Spain, while heavy rain and snow affect the Alps

13 05 2015

Parts of Spain, Portugal and southern France are experiencing unusually high temperatures at the moment. On Tuesday, Seville recorded 38C, and today will be another very hot day for the time of year, with temperatures widely expected to reach the low to mid 30s Celsius.

Met Office Global Model mean sea level pressure and temperature

Met Office Global Model mean sea level pressure and temperature

The hottest conditions will be across the Andalucía region of southern Spain. If temperatures reach or exceed 40C in Seville today this will be a new May record. Cooler conditions will gradually spread from the north tomorrow, although another very hot day is likely in southern Spain. Temperatures are then expected to return closer to average in all regions by Friday.

Meanwhile, southern Germany, Switzerland, Austria, and northern Italy are at risk of heavy rainfall over the coming days, with heavy snow possible on Friday across the Alps. Up to 150mm of rain could fall within 48 hours, possibly leading to flash flooding and landslides in this mountainous region of Europe, as well as increasing the avalanche risk due to fresh snowfall.

Whilst neither of these two weather events in Europe will affect the UK, we are expecting some heavy rain of our own on Thursday. The band of rain will move across southwest England during the early hours and edge slowly northeastwards through the day, but become almost stationary across parts of Wales, central-southern and southeast England. However, northern England, Northern Ireland and Scotland will remain largely dry and fine.





More warm weather this week – but what’s in store for the summer?

13 04 2015

This week is set to see some unseasonably warm weather for parts of the UK – with temperatures expected to climb to the low to mid-20s Celsius in the south on Tuesday and Wednesday.

Warm air flowing up from the south west will combine with high pressure, bringing settled conditions and sunny spells for many.

Warmest days of the year so far

This week’s above average temperatures follow on from a similar spell last week, which saw temperatures top out at 21.9C at St James’s Park in London on Friday.

This was the ‘warmest day of the year so far’, but It looks like Tuesday and Wednesday will top that – which is to be expected as we head through spring and edge closer to the start of summer.

Unfortunately, the weather we get in April doesn’t necessarily tell us anything about the kind of summer we can expect. We’re still in the midst of spring, so it’s far too early to say what the months of June, July and August may hold.

Summer ‘heatwave’ speculation

That hasn’t stopped speculation about heatwaves, the warmest summer ever and record temperatures in the media. Some stories cite our three month outlook for contingency planners as proof of the impending heatwave, but this is in no way an accurate reflection of what it shows.

The outlook shows probabilities attached to different scenarios for temperature and rainfall over the whole three-month period it covers. This is useful for those who use probabilities to plan ahead on longer-timescales, but not very useful for deciding where and when to go on your UK summer holiday, for example.

What does the longer outlook show?

Our current three month outlook does show that above average temperatures are more likely than below average temperatures for the April-June period. The outlook is essentially the scientific equivalent of factoring the odds on a horse race and, just like a horse race, the favourite doesn’t always win.

It’s also important to note that above average temperatures over a three-month period could come about in a variety of ways in terms of actual weather – we can still see warmer than average temperatures when it’s cloudy and wet, for example. Also, even in an above average three-months not all individual months would need to be above average.

This just reinforces the point that the contingency planners outlook doesn’t tell us what specific weather we are going to see at a specific location. For the best information on the weather ahead, people should use the Met Office’s 5-day weather forecast supplemented with our 30-day outlook.

By keeping up to date with the latest forecast, you’ll always have the most up-to-date and accurate view of the weather in store for the UK.





How will ex-Hurricane Cristobal affect the UK’s weather next week?

27 08 2014

The third tropical storm in the North Atlantic, Cristobal, has been making some headlines about its potential positive impact on us here in the UK – so what’s actually happening?

Cristobal is currently categorised as a hurricane and is currently between Bermuda and northeast Florida in the western Atlantic.

The storm is forecast to move north-east across the Atlantic over the coming days, changing to an ex-hurricane as it moves away from the warmer waters where it formed.

However, unlike ex-Hurricane Bertha which moved straight to the UK and brought strong winds and heavy rain to much of the British Isles, ex-Hurricane Cristobal is set on a very different track.

Instead it is forecast to move towards Iceland, staying well away from the UK as you can see from the forecast pressure chart below.

Forecast pressure chart for 1pm on Sunday 31 August shows ex-Cristobal heading towards Iceland.

Forecast pressure chart for 1pm on Sunday 31 August shows ex-Cristobal heading towards Iceland.

As Cristobal tracks to the north-west of the UK it could bring stronger winds across northwestern parts of Scotland for a time and there will also be some rain moving across the UK on Sunday into Monday.

It will have a longer lasting and more positive impact on our weather, however, as the track of the storm will result in an area of high pressure building further to the south and over the UK.

This high pressure will be maintained through next week as the jet stream moves to the north of the UK, bringing settled conditions across the country.

At this time of the year, high pressure generally brings dry and fine weather with some spells of sunshine, and that’s what we expect to see from around Tuesday next week.

With high pressure, daytime temperatures could reach the low to mid 20’s Celsius in places. This warmth will be especially noticeable following the cool conditions of late.

This spell of warm weather, however, doesn’t fit the definition of an Indian Summer – which you can read about on our website.





July makes eight warm months in a row

1 08 2014

This July was the eighth month in a row which has seen warmer than average temperatures for the UK. It was both sunnier and warmer than average, but not as much as July last year, according to provisional full-month statistics from the Met Office.

Figures for the whole month show that the UK mean temperature was 16.3C, which is 1.2C above the long term (1981-2010) average.

This ranks it as the 8th warmest July in our national records, joint with 1933. It’s worth noting that last July was warmer (17.0C, ranked 3rd), and this year is well short of the record warmest July of 2006 (17.8C).

Sunshine hours for the UK totalled 228.7 hours, which makes this the 6th sunniest July in records from 1929 – but, again, it’s not as sunny as last year’s July (248.7 hours, ranked 3rd), and is well off the record set in 1955 of 256.0 hours.

Rainfall was also below average, with this month’s UK total of 64.1 mm making 82% of the ‘normal’ amount we’d expect for the month. It was the driest July since 2006, marginally drier than last July, but there are many drier Julys in the records.

The rainfall patterns have been variable, with some parts of the country, such as the South West of England and west Wales, being much drier than average while others, such as parts of the South East, being much wetter.

Much of the rain has been from intense thundery downpours. On 20th July, Norwich Airport recorded 45.8mm in one hour, three-quarters of the ‘normal’ amount for the whole month.

Here are some other top weather facts from this July:

  • Highest temperature: 32.3C at Gravesend, Kent on the 18th
  • Lowest temperature: 1.2C at Braemar, Aberdeenshire on the 6th
  • Wettest day (midnight to midnight): 46mm at Northolt, Greater London on the 28th
  • Sunniest day: 16.1 hours at Glasgow, on the 9th
  • Strongest gust: 58mph at Warcop, Cumbria on the 18th

You can explore figures and statistics about the UK climate, including our national records dating back to 1910, on our climate pages.

The table below shows the provisional full month figures for July:

  Temperature (C) Sunshine (hours) Rainfall (mm)
July Provisional Actual Diff from avg Actual % of avg Actual % of avg
UK 16.3 1.2 228.7 133 64.1 82
England 17.6 1.3 251.1 130 53.1 85
Wales 16.2 1.0 238.6 133 53.7 58
Scotland 14.4 1.2 200.0 142 85.4 86
N Ireland 15.7 1.1 166.0 118 61.1 75




July 2014 in top ten warmest and sunniest

30 07 2014

This July is set to finish amongst the top ten warmest and sunniest in records dating back to 1910, according to early Met Office statistics.

Figures from the 1st to the 28th of the month show temperatures are slightly higher than normal, with a UK mean of 16.3C which is 1.2C above the 1981-2010 average.

If the month were to finish like that, it would be the joint 8th warmest in the record dating back to 1910 – but is well short of the record-breaking 17.8C set in 2006.

UK map showing hours of sunshine from 1-28 July 2014 compared to the full-month 1981-2010 average.

UK map showing hours of sunshine from 1-28 July 2014 compared to the full-month 1981-2010 average.

Sunshine hours for the UK are well above average, with 210 hours so far – which is 122% of the average we’d expect for the whole month. This means it is currently ranked as the joint 10th sunniest July in the record, and it’s likely to climb higher once the final few days of the month are included.

However, this July is unlikely to break the record of 256 hours of sunshine set in 1955.

Rainfall has been below average for the UK – but not by a record-breaking amount. The UK has seen about 59mm so far, which is 76% of the full month average – you’d normally expect about 90% at this stage.

That means this month currently ranks as the 29th driest July on record – and it’s likely to move closer to the mid-table due to any rain in the final few days of the month.

South west England and southern parts of Wales have seen the least rain compared to usual, with 42.6mm for the region making up just 53% of the full-month average.

  Mean temperature Sunshine
Rainfall
1-28 July Actual (celsius) Diff from avg Actual (hrs) % of avg Actual (mm) % of avg
UK 16.3 1.2 210 122 59 76
England 17.6 1.3 228.1 118 51.7 83
Wales 16.2 1 219.4 123 47.9 52
Scotland 14.4 1.2 187.3 133 75.1 75
N Ireland 15.7 1.1 152.5 109 53.4 66







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