How wet has this September been?

The latter part of September saw some exceptional rainfall in parts of the UK which caused disruption and flooding at times.

With such a great deal of rain falling in a short period of time, some people have asked whether it will make September one of the wettest in our national records going back to 1910.

Provisional early statistics up to 26 September show this isn’t the case, however, with the month looking set to be slightly wetter than average – but by no means a record breaker.

Up to the 26th, UK rainfall is 96.3 mm – which is 100% of the full month average. After 26 days we would, assuming rain falls fairly evenly through the month, expect this to be around 87%.

Of course, rain doesn’t always fall evenly throughout a month – as we saw this September. The first three weeks saw relatively little rain in many areas, but then a particularly active weather system brought four days of persistent heavy rain.

Northern parts of England were particularly badly affected by this, as you can see in the rainfall map below. In the map you can see a band of blue colours across northern England denoting above average rainfall for the month, whereas much of the country is coloured white to denote near-average amounts.

Two brown areas, one across central Scotland and the other in East Anglia, show it has been drier than average here – even despite the heavy rain in the latter part of the month.

 

Temperatures up to the 26 September are also fairly ordinary, being slightly below average. Mean temperature for the UK is 12.2 °C, which is 0.5 °C below the long-term average for the month.

While September looks set to be slightly wetter and cooler than average, the good news is sunshine hours were slightly up – with the UK having seen 126.1 hours of sunshine, 101% of its whole-month average.

Again, we’d expect it to be around 87% after 26 days, so we’re ahead – but not by a record-breaking amount.

So this September is set to go down as a fairly average month overall, but – as is often the case – this belies some very stark contrasts and some less-than-usual weather.

Met Office provisional 1-26 September figures
mean temperature sunshine duration rainfall
Actual Difference from 1981-2010 average Actual % of 1981-2010 average Actual % of 1981-2010 average
degC degC hours % mm %
UK 12.2 -0.5 126.1 101 96.3 100
England 13.2 -0.5 145.2 106 80.6 116
Wales 12.1 -0.8 124.5 97 115.3 99
Scotland 10.4 -0.5 98.6 94 117.2 86
N Ireland 11.8 -0.5 105.3 93 94.0 103
England & Wales 13.1 -0.5 142.3 105 85.4 112
England N 12.4 -0.4 124.0 98 121.4 150
England S 13.7 -0.5 156.4 110 59.0 93
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