A heatwave will serve the hottest ever start to Wimbledon, with temperatures due to hit 35C.
Sunday may reach 31C in parts of southern England, but Monday will be even hotter, with highs of 34C in central and eastern England, forecasters say.
Parts of south-east England could then hit 35C on Tuesday, forecaster Matthew Lenhert said, which would be hotter than Barbados.
Wimbledon is set for its hottest opening day on record on Monday and could even see the highest temperature ever recorded during the tournament.
The hottest ever Wimbledon day was on July 1 2015, when temperatures reached 35.7C.
The warmest opening day on record was on June 25 2001, when temperatures hit 29.3C.
The hottest day of 2025 so far was recorded on June 21 in Charlwood, Surrey, when temperatures hit 33.2C.
Tropical nights are also in store for many, with temperatures overnight not dropping below 20C, Mr Lenhert said.
Fresher air is then expected to move in from the west in the middle of the week, bringing an end to the heatwave.
It comes as a second amber heat health alert in two weeks came into force on Friday.
The alert, which covers London, the East Midlands, South East, South West and East of England, will last until 6pm on Tuesday.
The UK Health Security Agency (UKHSA) also issued a yellow alert for Yorkshire and Humber and the West Midlands for the same time period, with the agency warning of significant impacts across health and social care services.
An amber alert was previously issued for all regions in England on June 19, the first time it had been used since September 2023.
An official heatwave is recorded when areas reach a certain temperature for three consecutive days, with thresholds varying from 25C to 28C in different parts of the UK.
London Fire Brigade assistant commissioner Thomas Goodall said: 鈥淟ondon is already facing its second heatwave of the year and we know that people will be looking forward to getting outside to enjoy the wonderful weather.
鈥淏ut the high temperatures and low rainfall in recent months means the current risk of wildfires is severe.
鈥淪o far this year, firefighters have responded to around 14 wildfires in the capital.
鈥淭here have also been countless call outs to smaller fires involving grass, trees and in other outdoor spaces, as well as in people鈥檚 gardens.
鈥淒uring this latest heatwave, it is important everyone acts responsibly to prevent fires from occurring.
鈥淎s the weather has been so dry, it only takes a few sparks to lead to a fire spreading rapidly.
鈥淚n London, this is can be dangerous because so many of our green spaces lie close to homes and other properties.鈥
There will be a 鈥渕arked difference鈥 in north-western parts of the UK however, with cloud and heavy rain in parts of Northern Ireland and Scotland, where temperatures will stay in the mid to high teens, Mr Lenhert said.
The hottest ever July 1 on record was in 2015, when the temperature hit 36.7C.