A total of 72 out of 92 UK counties saw the hottest June on record, as the Met Office has confirmed last month’s record breaking temperatures were due in part to climate change.
Temperatures in June surpassed previous records dating to 1884, including previous highs set in June 1940, as well as June 1976 – which is currently the second-warmest June on record.
The “fingerprint of climate change” was on these temperatures, the Met Office said, as swathes of the UK observed record-breaking heat – and the high temperatures affected a significant area, Met Office said, including Orkney, Warwickshire, Surrey, Somerset and Cornwall.
The average mean temperature is 15.8°C for June 2023, 2.5°C above average. The previous record of 14.9°C was in 1940, and then matched again in 1976. The record for 2023 eclipsed the previous by 0.9°C, while the previous top three Junes were separated by just 0.1°C.
Paul Davies, Met Office climate extremes principal fellow and chief meteorologist, said the chances of seeing record-breaking temperatures has increased with climate change, and that exceeding average temperatures would become more and more frequent – to the extent that it could occur every other year.
The Met Office conducted a rapid study, which found the chance of observing a June beating the previous record of 14.9°C, like the UK has this year, has at least doubled since around 1940.
Mr Davies said: “We found that the chance of observing a June beating the previous joint 1940/1976 record of 14.9°C has at least doubled since the 40s. Alongside natural variability, the background warming of the Earth’s atmosphere due to human induced climate change has driven up the possibility of reaching record high temperatures.
“Using our UKCP18 climate projections, we can also see that there is a difference in the frequency of these sort of extremes, depending on the emissions scenario we follow in the future.
“By the 2050s the chance of surpassing the previous record of 14.9°C could be as high as around 50 per cent, or every other year. Beyond the 2050s the likelihood is strongly governed by our emissions of greenhouse gasses, with the chance increasing further in a high emissions scenario but levelling off under mitigation.”
It was also the sunniest June in the UK since 1957, and it was dry – with only 68 per cent of average rainfall falling across the UK. Wales was particularly dry, recording just over half of its average monthly rainfall with 46.7mm (51 per cent of average).
The Met Office’s Mark McCarthy said the persistent warmth of the month was “striking”.
“June started with a good deal of high pressure and temperatures initially around average for many, but once that subsided, warm, humid air began to influence temperatures, with 32.2°C the highest temperatures reached.
“What’s striking is the persistent warmth for much of the month, with temperatures widely into the mid-20s Celsius for many and even into the low-30s at times.”
Eight of the 12 calendar months now have an average temperature record set since 2006 in a series which dates back to 1884.
A marine heatwave in the North Atlantic, including waters around the UK, also played an underlying role in the record-breaking temperatures on land.
Dr Richard Hodgkins, senior lecturer in Physical Geography at Loughborough University, said the record-breaking temperatures in June were fitting into expectations of longer heatwaves due to climate change – which carried dangerous consequences.
Last month, an unusual build up of heat over the North Atlantic caused the jet stream high in the atmosphere to “stick” in a state that allowed warm, easterly air to dominate the UK for weeks, Dr Hodgkins said.
“In a warmer climate, this is very much the sort of pattern we’d expect to see more often, and if it occurred in the warmer months of July or August, it could lead to extreme heat conditions, with health risks for outdoor workers, the elderly and the vulnerable, together with increased wildfire risks and drought.”
He expected the Met Office’s observations linking the June temperatures to climate change to be accurate.
“Breaking the record by almost a whole degree is statistically very unlikely in the absence of climate change – records usually creep up by small fractions of a degree. The UK is one of the best-monitored places in the world meteorologically, so we can be confident in the data.”
