Forecasters say there is a "fairly comfortable" chance that Sunday will top Saturday's record-breaking temperatures.
West London is set to swelter for the Wimbledon men's final, after thermometers at Heathrow and Kew Gardens in the capital nudged 28.1C (82.6F) on Saturday.
Those temperatures are set to be put in the shade today as the mercury soars to 30C (86F).
Forecasters predict that most of the UK will be bathed in sunshine, with just a small chance of a shower across the Pennines and Cumbria.
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Hottest Day
Matt Dobson, a forecaster with MeteoGroup, the weather division of the Press Association, said: "Most areas, particularly in the southern half of the UK, will have another glorious day with plenty of sunshine and obviously very warm again.
"We are looking at temperatures of between 26C (78.8F) and 29C (84.2F) across many inland parts of England and eastern Wales, and we could just see 30C (86F) likely in west London.
"Yesterday was the hottest day of the year so far, and it is fairly comfortable that we are going to beat that today, with the favourite spot to do so being west London and the Thames Valley.
"The North is not quite as warm, with a bit more cloud than the South, but it will still be pleasant."
Dobson said that the forecast remained fine for the coming days, but temperatures would fall off to something more comfortable by the middle of the week.
He said: "Rather than the heatwave continuing to intensify it will just remain lovely and glorious weather, and will gradually become less hot by Wednesday or Thursday."
Yesterday, the hot weather also saw the number of 999 calls to one of the country's biggest ambulance services surge.
West Midlands Ambulance Service said it had dealt with 14% more calls than its New Years Eve' shift, which is traditionally its busiest time of the year.
Diana Lee, assistant chief ambulance officer, said: "Historically, when the weather is good, there is greater demand on both the ambulance service and the NHS as a whole.
"Yesterday was no exception and saw ambulance crews and control room staff work flat out to deal with 14% more 999 calls than on New Years' Eve, traditionally the busiest day of the year."