Sunday is set to be the hottest day of the year, with forecasters predicting temperatures will hit 30C (86F).
Britons have been enjoying a weekend heatwave, basking in sunshine on Saturday as the mercury rose into the high 20s.
The warm weather prompted bookmakers to cut the odds of a record-breaking summer.
The hottest day of the year so far was May 24, when the temperature reached 28.8C (84F) at Heathrow Airport and the Olympic Park in east London.
Thousands made the most of the conditions on Saturday, flocking to beaches and parks or soaking up the rays with barbecues in the garden.
Temperatures reached a high of 28.6C (83.5F) at Charlwood in Surrey as large swathes of England got into the swing of summer.
The sweltering conditions come as millions prepare to watch England take on the arch enemy, Germany, in the World Cup.
Thousands of revellers at Glastonbury music festival have also been able to ditch their wellies for the first time in years and party in the sunshine.
Ladbrokes offered 3/1, cut from 7/2, that the highest ever UK temperature of 38.5C (101.3F) recorded at Brogdale, near Faversham, Kent, in 2003 will be beaten.
Spokesman Nick Weinberg said: "We're feeling the heat as temperatures continue to soar."