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Stats for September 2025 (compared to 1991-2020 mean)
September 2025 was very close to the long term mean temperature wise. It was the first month since January 2025 to be so. It reached 20 degC on 8 days, the last being the 19th. There were no air frosts recorded, but grass frost was locally reported.
It was the wettest month since September last year. It rained on 18 days, with the 20th being the wettest day at 32.5mm. (only 0.1mm different to the official total at Durham University Observatory). It contributed nearly half of the overall monthly total of 70.3mm. This made it a wetter-than-average September too.
It wasn’t anywhere near the wettest September day though (although it was the 13th wettest September day since 1850). This occurred in September 1976.
Temperature
Mean Temperature : 13.2 degC (-0.2)
Mean Max Temp : 17.7 degC (+0.3)
Mean Min Temp : 9.6 degC (-0.3)
Warmest Temperature : 22.2 degC on 7th
Coldest Temperature : 3.3 degC on 22nd
Days reaching 20 degC : 8
Air Frosts : 0
Rainfall
Total Rain : 70.3 mm (+13.4)
Wettest Day : 32.5 mm on 20th
Rain Days : 18 (+9)
Barometer
Average Barometric Pressure : 1012.0 mb
Highest Barometric Pressure : 1031.5 mb on 24th
Lowest Barometric Pressure : 987.1 mb on 15th
Sunshine
Total Sunshine Hours : 150 (from Durham Observatory)
Month Index : 212 (based on Temp, Rain and Sunshine)
Trevor Harley’s summary of UK Weather in September 2025.
In a change to recent months, September 2025 was cooler and wetter than average. The areas of high pressure that had dominated the year so far slipped away allowing depressions to cross the country.
It was an unsettled first three weeks, when it was particularly wet in the west. It reached 27.8ªC at St. James’s Park on the 19th, the highest temperature of the month. It then became more settled, before the north saw more rain at the end of the month.
It was at times windy and thunder, and there were some low night temperatures in the final week. The UK overall had 132% of the average rainfall, with many areas reaching the monthly average total by the middle of the month.
It was particularly wet in the Lake District, with Cumbria recording 198% of the average for September (making it the fourth wettest on record).
The highest rainfall reading was 87.8 mm at Achnagart (Ross & Cromarty on the recording day ending on the 12th. The UK as a whole was 0.1ºC below average (12.8), with warm and cool spells tending to cancel each other out.
The lowest temperature of the month was -5.0 at Tomintoul (Banffshire) on the 29th. The UK as a whole was quite sunny (110%), particularly over England and Scotland. The strongest gust of wind was 78 mph at the Needles on the Isle of Wight.
Durham University Observatory Summary for September 2025
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