After reaching temperatures of 29.1C (84.4F) in the capital on Thursday afternoon – the hottest April day since 1949 – temperatures will move down to highs of around 25C (77F) on Friday.
Despite the drop, this is still way above the average average temperature for April which is 11.4C (52.5F).
However, temperatures are set to fall across the UK from the beginning of next week, with some showery outbreaks predicted.
Thunderstorms have been forecast across England and Wales on Saturday and runners of Sunday’s London Marathon have been advised not to take part in fancy dress because of the potential to overheat on what could be the warmest race day on record.
Highs of up to 23C (73.4F) are predicted on Sunday, but rain showers coming in from the west may reduce the temperature by a degree or two.
The hottest London marathon on record was 22.7C (72.9F) in 1996, according to the Met Office.
Race director Hugh Brashar said People are urged to wear sunscreen and appropriate clothing. Listen to your body. Change your race plan.
Extra water, ice and shower stations have also been added to the 26.2 mile (42.2km) route.
Running the #LondonMarathon this weekend? Here is the latest forecast pic.twitter.com/eVlr6vWWCT
Celebrities expected to run the course across the capital this year include ex-glamour model Katie Price, radio DJ Chris Evans and celebrity chef Gordon Ramsay.
Sky News Weather producer Joanna Robinson said Sunday was likely to be an unsettled day, with warm and muggy weather in the southeast.
Cooler and more changeable weather is then set to arrive next week.
News Source SkyNews