The year 2025 was both the hottest and 2nd hottest year on record in the UK.  Last year, I used a CUSUM Chart to conclude “if the calendar year average is greater than 9.48 degrees Celsius and the meteorological year average is greater than 9.33 degrees Celsius … (this will) signal an upwards trend change“.  By co-incidence, the average 24-hour temperature across the UK in 2025 was 10.09 degrees Celsius for both the calendar (Jan to Dec) and the meteorological (Dec to Nov) years which is clearly higher than these thresholds.  It’s only taken me four years of writing to conclude a new upward trend in UK temperatures has begun.

[Read more…] about UK Weather Trends #39 – Annual Temperatures in 2025