WIREDGOV

Summer 2025 went down as provisionally the warmest on record for the UK, but how accurate was the Met Office forecast through the season? We crunch the numbers to find out…

The warmest summer on record, drought status for many, thunderstorms and even Storm Floris; Summer 2025 brought its fair share of impactful weather.  

Summer is typically the season which can be hardest for UK forecasters. A lack of underlying global drivers, as well as the prominence of small-scale but impactful weather like thunderstorms, means that developing the forecast, especially at longer ranges, can be a complex task. Small-scale features like thunderstorms can often significantly influence accuracy metrics, not only for rainfall, but also for wind speed and direction.  

Here, we assess how accurate the forecast was through meteorological summer (June, July and August), as well as the impact it had on people, industry, and government.  

How accurate was the forecast through the season?  

Met Office forecast accuracy is routinely assessed in a wide variety of ways of ways, but the below figures are informed by forecast verification at around 120 sites around the UK, giving geographical spread across the UK. As a general rule, UK forecast accuracy increases incrementally and upcoming developments around new supercomputing infrastructure, satellite projects and the advancement of AI could accelerate these improvements in the coming years.  

Temperature forecasts are deemed to be ‘accurate’ if they’re correct within 2°C of the verifying observation.  

For maximum temperature forecasts in the season, 1-day forecasts were 93% accurate, with 73% accurate at the 5-day range. Of course, some of the most notable weather over the summer came in the form of heatwaves, when there may be particular focus on forecast accuracy. Of the maximum temperature observations that exceeded 30°C over the summer, over 90% of the forecasts were forecasting temperatures above 28°C at three days ahead, and over 70% of the forecasts were forecasting temperatures over 28°C at four days ahead. 

Minimum temperature forecasts were similarly accurate. 1-day forecasts were 89% accurate by this metric, with this dropping to 70% at the 5-day range.  

Wind speed is assessed as accurate if it’s within five knots of the verifying observation. 1-day forecasts were 93% accurate, with 84% accuracy at the 5-day range.  

Wind direction is deemed as accurate if it’s within one compass point on a 16-point compass (22.5 degrees). 1-day forecast accuracy for this was 88% accurate, with this dropping to 57% at the 5-day range.  

Met Office Director of Science Simon Vosper leads the scientific work on weather modelling, which is the basis of forecasting. 

He yesterday said:

“Summer is famously tricky for weather forecasting in the UK. A lack of global drivers compared to winter, coupled with the potential for small-scale impactful weather, means that it can be a challenging period to forecast. However, accuracy above 90% for the majority of 1-day forecast metrics and above 70% for the majority of 5-day metrics is good performance.” 

“I’m immensely proud of the work of our teams in ensuring forecast accuracy through the season, working through the details and complexities of what the UK weather can throw at us. I’m particularly pleased to see the accuracy around the temperature figures, especially given the importance of this as we experience more frequent and prolonged heatwave events.” 

Click here for the full press release