Much of Britain continued to swelter in warm sunshine, but forecasters warned showers are likely as the week goes on.
South East England again experienced the best of the weather, with maximum temperatures 9C above the seasonal average.
However, it was slightly cooler than Sunday, when the mercury hit 30.9C (87.6F) at Gravesend in Kent, making it the UK's hottest day of the year so far.
Temperatures reached 28C (82F) in Norwich and 27.4C (81F) at the Olympic Park in east London by mid-afternoon on Monday.
Aisling Creevey, a forecaster with MeteoGroup UK, the weather division of the Press Association, said: "It's still really warm - about nine degrees above average for this time of year in the South East."
People in London were urged to take extra care in the hot weather.
Emergency calls to London Ambulance Service (LAS) shot up by more than 20% on Saturday and Sunday compared to the previous weekend as football fans drowned their sorrows in the sunshine after watching England get knocked out of the World Cup.
Jason Killens, LAS deputy director of operations, said: "In these high temperatures I would urge Londoners to take care in the sun.
"Drinking plenty of water and avoiding the sun at the hottest time of the day are both simple measures to avoid becoming a casualty of the sunshine."
The western side of the country will experience lower temperatures and the bulk of the rain this week.