The first heat-health alerts of the year will come into effect later, with Met Office warnings for thunderstorms also in place over the next few days.
The yellow heat alerts, issued by the UK Health Security Agency (UKHSA), cover the east of England, London, East Midlands and south-east England from 21:00 BST on Thursday until 08:00 on Sunday.
Temperatures on Friday will likely match the previous hottest day of 2025 so far – when 29.3C (84.7F) was recorded in Kew Gardens on 1 May.
The Met Office has issued three yellow warnings for thunderstorms for different parts of the country.
They are in place in:
- South-west England and Wales between 00:00 and 13:00 on Thursday
- Northern Ireland between 06:00 and 21:00, also on Thursday
- South-east England between 15:00 on Friday and 06:00 on Saturday
The amount of rain will vary on Thursday, but some areas could have as much as 10-20mm (0.40-0.8in) in an hour which could cause some flash flooding.
The band of thundery showers will move northwards through the day and evening, with the showers less likely to be thundery over Scotland on Thursday night.
On Friday afternoon, thunderstorms are forecast to hit south-east England and East Anglia regions, with torrential downpours of 30-50 mm of rain expected.
This could lead to surface water flooding, made worse by the recent dry spring.
The thunderstorms could even form in lines, with hail, lightning and gusty winds possibly causing further problems.
Meanwhile, temperatures are expected to surge in parts of eastern England with the heat and humidity combining to bring thunderstorms.
Friday’s peak temperatures will reach 28-29C and will likely be recorded somewhere in south-east England or East Anglia.
A southerly wind will continue to drag in some very warm air from the near continent where temperatures have been over 30C, and over 40C in some parts of Spain.
With cloud cover in the afternoon and thunderstorms moving on southerly wind, it will be hot and humid with the cloudiness limiting the daytime heating.
It has been the warmest spring – March, April and May – on record for the UK as a whole.
It was also the sunniest spring on record for Northern Ireland, Scotland and Wales, and the second sunniest in England.
The heat-health alert means that there is likely to be increased use of health care services by vulnerable people and an increased risk to the health of people aged over 65 years or with pre-existing health conditions, including respiratory and cardiovascular diseases.
