It could be the hottest day of the year so far, with forecasters predicting temperatures to soar to as high as 32C (89.6F).
Large areas of Britain will bask in sunshine with the hottest regions being in east and south-east England, which will see temperatures rivalling those of the Caribbean.
Most of the UK will see temperatures in the high 20s, albeit with some showers in the west and Wales and cooler temperatures in Scotland and Northern Ireland.
The hottest day of 2012 recorded so far was on July 25, when it reached 31.4C (88.5F) at the Olympic Park in east London.
It will mean a warm start to the Premier League season, with games taking place including Arsenal v Sunderland at the Emirates, Newcastle United v Tottenham Hotspur at the Sports Direct Arena and West Bromwich Albion v Liverpool at the Hawthorns.
It is also set to be a hot third day of the test match at Lords today between England and South Africa.
Other events taking place this weekend include the V Festival at Hylands Park, Chelmsford and Weston Park, Staffordshire, with headline sets from The Stone Roses and The Killers.
Other bands include Rizzle Kicks, The Enemy, Pixie Lott, Dappy, The Human League and The Proclaimers.
Cyclists from the Team GB paralympic cycling team are due to take part in a 20km time trial at Blenheim Palace in Woodstock, Oxfordshire today as a warm-up for the Paralympic Games.
Tomorrow will present a more unsettled picture across much of the UK with showers spreading northwards over much of the UK, some of which could be heavy and thundery.
But temperatures could still reach 30C (86F) in London and 26C (78.8F) in other parts of the country.