t-test

UK Weather Trends #39 – Annual Temperatures in 2025

January 6, 2026 By Nigel Marriott

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.

UK Weather Trends #34 – Annual Temperatures in 2024

January 7, 2025 By Nigel Marriott

The 2024 calendar year was the 4th hottest year on record in the UK. Last year, I used a Control Chart to conclude “a step change upwards (in UK temperatures) has taken place but the pace of change is not yet clear“. I am now less confident in my conclusion after updating with 2024 data, especially when I look at temperature trends based on the meteorological year of December to November instead.

UK Weather Trends #29 – Annual Temperatures in 2023

January 4, 2024 By Nigel Marriott

The 2023 calendar year was the 2nd hottest year on record in the UK just behind the hottest year ever in 2022. Last year, I showed how a technique known as a Control Chart could be used to decide if the UK is now in a new warming trend and after adding 2023, my answer is now “a step change upwards has taken place but the pace of change is not yet clear“.

UK Weather Trends #24 – Annual Temperatures in 2022

January 3, 2023 By Nigel Marriott

The 2022 calendar year was the hottest year on record in the UK beating the previous high recorded in 2014. Does that mean that the UK is starting a new warming phase? Using a technique known as a Control Chart, I show the answer is “Not Yet“.