Why Hurricane Debby could bring UK temperatures back to the mid-30s

Pic from ITV Anglia Viewer
Rosemarie Jessop - Horringer Sunflower Field in Suffolk.
Credit: Rosemarie Jessop

The hottest weather of the summer is on the way - and it'll bring with it the highest humidity we've experienced so far this year.

Temperatures are expected to peak through Sunday and Monday, with the heat and humidity lingering, making it feel like tropical weather overnight.

Temperatures will widely reach 27C to 30C (81-86F) across much of central and southern parts of the UK. However, there will be an area of up to 34C (93F) somewhere in a line from London to north Lincolnshire and approximately 60 miles either side of that.

Within that band, there is even the possibility that temperatures could reach as high as 36C (100F).

Peak temperatures, shown in purple, could reach 34C widely, with up to 30C in the green shaded area. Credit: Met Office

The temperature record so far this year is 32C (90F) on 29 July in Kew Gardens with the same temperature again at Heathrow Airport on 30 July - a record which is likely to be broken.

The reason for the hot weather is the buckling of the jet stream from ex-Hurricane Debby, but the heat and humidity will come from northern parts of Europe as air recirculates northwards towards the UK.

Buckling jet stream bringing hot air from the continent Credit: ITV Graphics

The likes of York, Sheffield and Lincoln will see temperatures of 27C (81F) on Sunday, while it could reach 29C in Cambridge and London.

But Monday it is likely to be even hotter with the peak of the temperatures occurring before a quick breakdown in weather.

Heat health alerts will be in place for much of central and southern England.

But just as quick as the hot weather arrives, it will be swept away by Tuesday and there will be some thundery rain mixed in as the hot is replaced by fresher air.

This follows a very similar pattern to the summer so far with brief cold, warm and hot spells of weather interchanging.

If temperatures go higher than 33.5C, it will be the hottest day for approximately two years. The hottest day of the year in 2023 was 10 September when 33.5C was reached.

It was a memorable year in 2022 when 40.2 (104.4F) was reached on 19 July. The mercury also hit 33.5C on 13 August that year.

Where is the hot weather coming from and why is it so brief?

Ex-Hurricane Debby is moving northwards along the eastern seaboard in the USA. Debby has already caused death and continues to bring intense rainfall which will continue and danger to life with state of emergency declared across Florida, Georgia and North and South Carolina.

Debby is the fourth named tropical storm of the 2024 Atlantic Hurricane Season and was a category one hurricane before making landfall. It was first reported as an area of interested by the National Hurricane warning centre on 26 July.

A category 1 hurricane is the lowest level of hurricane but in this case it is not the wind causing devastation, it is the amount of rainfall.

As Debby moves up the eastern seaboard, the energy from the storm as well as the pattern up at the jet stream level will combine to cause a buckle in the jet stream across the Atlantic.

This change in orientation will allow air from northern France to loop back on itself, bringing some very humid and hot weather.

Left: Widespread heat and humidity, and, right, the areas most likely to see 30C. Credit: Met Office

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