The Met Office has said there's a 50/50 chance that the UK will see temperatures reach 40°C again within the next 12 years, as extreme heat becomes more likely due to the climate crisis. Experts also warned that even higher temperatures, potentially reaching 45°C (113°F) or more, could occur under current climate conditions, and that future heatwaves might last for a month or longer.

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The UK experienced its first-ever 40°C day during the intense heatwave and drought of summer 2022, with temperatures peaking at 40.3°C in Coningsby, Lincolnshire, on 19 July. This broke the previous high of 38.7°C set in Cambridge in 2019. Fire services in London, Leicestershire, and South Yorkshire declared major incidents after numerous fires emerged, destroying homes, schools, churches, and farmland. The blazes also caused significant disruption to transport and power networks across the regions.

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During the peak of the heatwave, over a four-day period, more than 1,000 additional deaths were recorded among older adults, with the total number of heat-related deaths in England that summer surpassing 3,000. According to Met Office analysis, which used global climate models to simulate a wide range of possible outcomes under current conditions, the likelihood of the UK experiencing 40°C temperatures has been rising sharply.

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Research published in the journal Weather found that temperatures reaching 40°C are now over 20 times more likely than they were in the 1960s, and the risk has nearly tripled since 2000. As the climate crisis continues to drive temperatures higher, the Met Office warned there is now a 50/50 chance of experiencing another 40°C day within the next 12 years. They also stated that even higher temperatures, up to 46.6°C, are now considered possible.

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Dr Gillian Kay, who is a senior scientist at the Met Office and the lead author of the study, said: “The chance of exceeding 40C 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 40C 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.”

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The study also examined heatwaves and found that far more intense extremes are possible under the current climate conditions. According to the climate model, as many as two-thirds of summer days in south-east England could exceed the heatwave threshold of 28°C, with some heatwaves lasting over a month without a break. It also suggested that stretches of 12 consecutive days with temperatures above 35°C could happen. Met Office scientists said these results highlight the urgent need for better planning and preparation to cope with rising temperatures and extreme heat.

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Dr Nick Dunstone, a co-author of the study, said: “The well-known hot summer of 1976 had more than a fortnight above 28C, which is a key heatwave threshold in south-east 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.”

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