Met Office scientists have published a new study detailing the increasing likelihood of extreme temperatures in the UK, revealing that the chance of exceeding 40°C in the UK is accelerating at pace.

‘Rapidly increasing chance of record UK summer temperatures’, published in Weather journal, underscores the need for people and organisations to prepare for even higher heat extremes in the near future.

In July 2022, the UK experienced its first recorded temperature above 40°C, when Coningsby in Lincolnshire reached 40.3°C. The unprecedented temperature formed part of Europe's warmest summer on record. There were significant impacts, including wildfires, disruptions to transport and power systems, and increased mortality.

The approach taken in the study, called UNSEEN, uses a global climate model to create a large set of plausible climate outcomes in the current climate. This allows an assessment of current risk and how extremes have changed over the last few decades.

Chance of exceeding 40°C has been rapidly increasing

Dr Gillian Kay, Senior Scientist at the Met Office, and lead author said:

"The chance of exceeding 40°C has been rapidly increasing, and it is now over 20 times more likely than it was in the 1960s. Because our climate continues to warm, we can expect the chance to keep rising. We estimate a 50-50 chance of seeing a 40°C day again in the next 12 years. We also found that temperatures several degrees higher than we saw in July 2022 are possible in today’s climate.”

Image: Graph shows a below 1% chance of 40C in the UK in 1960,

around 2% by 2005, 3% by 2015 and 4% chance by 2023

Heatwaves above 28°C could persist for a month or more

The study also examines the length of heatwaves. Dr Nick Dunstone, Met Office Science Fellow and co-author of the study, commented:

“The well-known hot summer of 1976 had more than a fortnight above 28°C, which is a key heatwave threshold in southeast England. Our study finds that in today’s climate such conditions could persist for a month or more. These findings highlight the need to prepare and plan for the impacts of rising temperatures now, so we can better protect public health, infrastructure, and the environment from the growing threat of extreme heat."

The UK government's Climate Adaptation Research and Innovation Framework, sets out the need for improved understanding of climate extremes and tools for stress testing across key sectors.

‘Rapidly Increasing Chance of Record UK Summer Temperatures’ illustrates how large climate model ensembles can help by providing robust insights into the likelihood and nature of future high-impact events.