The week until Sunday was the first-ever time such a protracted heatwave had occurred in September, the Met Office said
The UK had an unprecedented seventh consecutive day of 30C heat on Sunday, the Met Office said, but some areas were already experiencing the end of the heatwave with heavy, thundery rain and warnings of more on the way.
Forecasters said there had never been a September heatwave on record as long-lived as this year’s episode. Sunday became the seventh consecutive day of 30 degree weather in the UK with 32.5C recorded in Cambridge.
Before that, according to Met Office data, the UK has only had three consecutive days of 30C weather in September on four previous occasions: 1898, 1906, 1911 and 2016.
Tom Morgan, a Met Office meteorologist, had predicted another day of temperatures above 30C, and the highest temperatures were expected in the home counties.
“It’s looking likely that we will see the seventh day of temperatures running at 30C or higher, which is unprecedented. We have never seen anything as long-lived in terms of a heatwave in September before,” he said.
Saturday was named the hottest day of 2023 in the UK with 32.7C recorded at Heathrow.
Many beaches were packed on Saturday and Sunday while those on boat trips in Cambridge used umbrellas to shelter from the sun.
Pets and animals struggled in the heat, however, and a number of weekend shows were cancelled, including DogFest, at Knebworth House near Stevenage. Organisers announced the cancellation with “a heavy heart” but said “these conditions are not in the best interests of dogs”.
Intense downpours followed the 2016 September heatwave and it is expected a similar weather pattern will follow this one.
A yellow thunderstorm warning spanning Northern Ireland, northern parts of England and Wales as well as southern and north-eastern Scotland was issued for most of Sunday afternoon.
Many parts of that area were forecast to experience modest rainfall but pockets of intense rainfall were expected, forecasters said, which could mean 70mm of water falling in less than an hour.
The Met Office said flooding of homes and businesses could happen quickly “with damage to some buildings from flood water, lightning strikes, hail or strong winds”.
The conditions could make driving difficult, lead to train and bus disruption, cause power cuts or isolate some communities because of flooding.
On Tyneside the travel plans of Great North Run participants and spectators were hit by flash flooding which led to the closure of South Shields Metro station and disruption across the network.
The weather warning is in place until 11.59pm on Sunday, but a separate yellow thunderstorm warning is in place for overnight until 6am Monday. That covers southern and central Scotland and includes the cities of Glasgow, Edinburgh and Perth.
A third weather warning was issued on Sunday afternoon for severe thunderstorms and strong gusty winds across the east Midlands and northern East Anglia.
The Met Office said the likely speed of the transit of the thunderstorms meant rainfall would be limited.
“However, frequent lightning, large hail (up to 2cm in diameter), and wind gusts of 40-50 mph are possible,” the Met Office said. The warning was due to expire at 6pm.
Looking ahead there will be a few thunderstorms on Monday, Morgan said. “But for the vast majority they will be a bit more scattered in nature than today.”