An amber heat warning is in force as parts of the UK prepare for temperatures up to 38C

A rare amber heat warning will come into force across parts of the UK on Thursday, with temperatures expected to climb as high as 38C.

The warning covers a large swathe of the country, including eastern England, London and the south-east, the Midlands and parts of Yorkshire and Humber. It will run from 09:00 BST until 23:59 BST.

Thursday is expected to be the peak of the UK’s fifth widespread heatwave of the year, with much of the warning area likely to see temperatures in the mid-30s Celsius.

The amber heat warning comes alongside amber heat health alerts from the UK Health Security Agency, which are already in place across the whole of England until 21:00 BST on Friday.

Those alerts warn of significant pressure on health and social care services, including a possible rise in deaths, particularly among people aged 65 and over and those with existing health conditions.

The searing temperatures could also cause disruption beyond health services. Power cuts, rail delays and air travel disruption are all possible as infrastructure comes under strain.

Forecasters have warned that the heat could lead to dehydration, heat exhaustion and other serious health effects, especially for vulnerable people.

The nights may bring little relief in some areas. A few tropical nights are possible, meaning temperatures may not fall below 20C as increasingly humid air spreads into western parts of the UK.

That matters because heat becomes more dangerous when the body has no chance to cool down properly overnight. Persistent high temperatures by day and night can place extra stress on people, particularly the elderly, young children and those with medical conditions.

The good news is that this heatwave is expected to be short-lived. Temperatures should begin to fall by the weekend, although they are still likely to remain average or slightly above average for mid-August.

The latest spell of extreme heat could also bring more temperature records.

Wednesday became the first day in August to reach 35C or more, making it the fourth consecutive month this year to hit that level.

If temperatures reach 36C or higher, 2026 will become the first year on record to register four separate days at or above that threshold. That would beat the previous record of three days, shared by 1990, 2003, 2020 and 2026.

A few places, including London, could reach 38C. If that happens, it would be the second time the UK has hit 38C this summer, matching the highest reading of the year so far, recorded in Lingwood, Norfolk, on 26 June.

It would also be tied for the hottest August day since 2003, when 38.5C was recorded.

The wider summer record is also in sight. If August temperatures remain average or above average for the month overall, this summer could replace 2025 as the warmest on record.

The combination of high daytime temperatures, humid nights and pressure on services explains why the warning level has been raised. Amber warnings are not issued lightly and are intended to signal a risk of serious impacts.

For millions of people, Thursday will be a day to avoid unnecessary heat exposure, keep homes as cool as possible and check on vulnerable relatives, neighbours and friends.

The heat may only last a few days, but at its peak it could be intense enough to affect health, transport and daily life across much of England.