Sadiq Khan triggers emergency weather response for London as UK swelters in record-breaking September heatwave

7 September 2023, 13:02

Sadiq Khan has issued an emergency weather response for the capital as the UK is set to see its longest September heatwave on record.

The Met Office has forecast up to seven days of temperatures above 30C across the country, with a peak of 33C on Saturday in London.

With heat records set to be broken across the country, London mayor Sadiq Khan has issued an emergency severe weather response in the capital.

The weather response has been set in place to help homeless people stay safe in the heat - it is typically activated in periods of extreme weather to provide emergency support for rough sleepers.

The previous UK record for the number of consecutive days above 30C in September is three days in a row, which has happened four times on record.

But as the UK braces to enter its fourth consecutive day above 30C on Thursday, the record is now on track to be broken.

“On four occasions in Met Office climate statistics has September had three consecutive days of temperatures above 30C,” Stephen Dixon of the Met Office said.

“Including [Wednesday], we're up to three on this event and expect to exceed 30C [on Thursday]. This would be the most consecutive days of temperatures above 30C in September.”

Read more: Exact day UK heatwave will end as thunderstorms predicted - as London braces for 32C scorcher

Read more: How your home appliances can heat your home up to 43C when it’s 32 degrees outside

And this won’t be the only record broken this week, as the September with the most 30C days on record - but not consecutive days - was in 1911, which saw five scorching days over the course of the month.

The UK is forecast to break this record too, as it is expected Saturday will become the sixth day in a row with temperatures of at least 30C.

Temperatures reached 32C in Kew Gardens, London yesterday, making it the hottest September day in the UK since 2016 and just 0.2C short of the hottest day of the year.

September's heatwave is likely to peak on Saturday with temperatures rising as high as 33C in London, the Met Office has said, although further north will be cooler.

That would make it the hottest day of the year, beating 32.2C in June, with the UK Health Security Agency issuing an amber warning for heat until Sunday evening at 9pm.

Met Office chief meteorologist Paul Gundersen said: "High pressure is situated to the southeast of the UK, which is bringing more settled conditions and temperatures well above average for the time of year.

"While the highest temperatures are expected in the south, heatwave conditions are likely across much of England and Wales especially, with parts of Scotland and Northern Ireland also likely to see some unseasonably high temperatures."

The heatwave is being driven by tropical storms pushing a high pressure system over the UK, with the jet stream having moved to the north and bending into what is known as an omega blocking pattern.

Named after the Greek letter omega because of its shape, this system occurs when an area of high pressure gets stuck between two areas of low-pressure to the west and east and also slightly south.

This has brought torrential rain and flooding for Spain and Greece but hot, dry and clear conditions for the UK and central Europe.

Met Office chief meteorologist Neil Armstrong said: "An active tropical cyclone season in the North Atlantic has helped to amplify the pattern across the North Atlantic, pushing the jet stream well to the north of the UK, allowing some very warm air to be drawn north.

"It's a marked contrast to the much of meteorological summer, when the UK was on the northern side of the jet stream with cooler air and more unsettled weather."