The Met Office and the UK Health Safety Agency (UKSA) have issued a heat alert warning as temperatures rise to 34ºC later this week.
The forecaster said a level 2 alert has been issued for the south and center of England from midnight on Friday to midnight on Sunday, with a level 1 alert lower than in the north of England.
The alert system is designed to help healthcare workers manage extreme temperatures.
The Met Office warned earlier this week that the British should prepare for the heat waves in the coming months, amid previous forecasts from the forecaster that they were becoming more likely due to the change. climate.
Meteorologists said parts of the south of the UK could reach 30 ° C (86 ° F) and even 34 ° C higher (93 ° F) in the south-east, while in the north-east and south Northwest temperatures are expected to rise to 28 ° C (82 ° F).
The highest temperature in the UK so far this year was 27.5 ºC (81.5 ºF) at Heathrow on 17 May.
Met Office Assistant Meteorologist Dan Rudman said temperature forecasts are unusual for this time of year.
“Many areas will also see some warm nights with minimum temperatures expected to be in their teens or even as low as 20 degrees over another night,” he said.
“The heat is the result of a combination of home-grown heating during the day due to high pressure, as well as a southerly airflow that introduces some of the continent’s warm air to the coasts of the United Kingdom “.
A heat wave is defined as three consecutive days of maximum daily temperatures reaching or exceeding the heat wave temperature threshold. The threshold varies in each county.
In March, the Met Office raised heatwave thresholds to eight counties in response to global warming that made the original thresholds obsolete.
Agostinho Sousa, head of extreme events and health protection at the UKHSA, said: “Temperatures are expected to reach 30ºC in some parts of the south on Friday and we want everyone to enjoy the warm weather safely when it arrives and is good health tips for dealing with warmer conditions.
“During periods of heat, it is especially important to continue to monitor those who are most vulnerable, such as the elderly and those with heart or lung disease.”
A spokesman for the Environment Agency said there was a low risk of drought, but warned that a hot, dry climate could put pressure on some areas.
NHS hot weather tips suggest that people stay out of the sun between 11am and 3pm, get hydrated, wear sunscreen and wear casual clothing.