Sunday is forecast to be the hottest day of the year so far in London, as temperatures are set to reach 30 degrees Celsius across the capital.
Despite earlier predictions that this week's hot weather would only last until the weekend, the UK heatwave is now thought to continue into the next week.
In London, Sunday and Monday are expected to record highs of 30 degrees during the day. According to the BBC, this will then cool off slightly to 26 degrees by mid-week.
Weather forecaster Darren Bett said that rainfall is most likely to occur in the south west of the UK, where low pressure is contributing to the region's cool down.
There is now a thunderstorm warning in place for between 6am and 10pm tomorrow in both the south west and in south Wales.
"What we will find over the weekend is that pressure will start to drop a bit. But still, most places will be dry," said Betts.
"Ahead of that, we are still drawing in some very warm, if not hot air. The wind direction changes a bit – get more of a southeasterly and that will increase the humidity in the south."
Watch how the map becomes even more orange as the afternoon progresses! Barely a cloud in the sky and certainly the potential to top 30 ºC in a few spots again #summer #heatwave pic.twitter.com/8NCd6oS3Hb
— Met Office (@metoffice) June 30, 2018
According to the Met Office, this will be the longest spell of 30-degree daily temperatures since the summer of 1976, as well as the UK's longest heatwave.