Temperatures are predicted to reach 30C at the weekend in central and southern Britain, almost double the usual average of 17C for this time of year.
The sunshine and blue skies are set to last into the middle of next week, according to the Met Office.
Spokeswoman Nicky Maxey said: “We are looking at temperatures for the central and south-east getting to 30C over the weekend, certainly the high 20s.
“Temperatures will warm up as we go into the weekend and the start of next week. We’re looking at warmer temperatures continuing into the middle of next week.
“This warm area is coming up from the tropical maritime air of the Azores in Portugal.”
In London and the south it will stay warm during the nights, with 13C predicted for Friday overnight and 18C overnight on Saturday.
“It will be quite humid and quite sticky and warm overnight as well as during the day,” Ms Maxey said.
The warm weather is unlikely to reach Scotland and the north, she added.
“As you go further north temperatures aren’t quite as high and we’re seeing a chance of some showers and more cloudy weather,” she said.
The highest temperature recorded in June was 35.6C in 1976 in Southampton.