A plume of scorching air from the continent will see Britain swelter in the warmest temperatures so far and close to the hottest on record.
After weeks of grey skies, rain and chilly winds the weather will make a dramatic u-turn towards the middle of next week.
A swathe of roasting air from Spain, where the mercury is nudging 44C (110F), will sweep into the UK on Tuesday and Wednesday.
Forecasters say there is a 50 per cent chance that next week will bring the hottest period of the year so far.
Leon Brown, forecaster for The Weather Channel UK, said: "The main story is a heatwave developing over Iberia this weekend and then the plume of heat moving north across France early next week and could reach the UK.
"There are some quite extreme forecasts for the UK next week, some bringing heat north next Tuesday and Wednesday to all of the UK with temperatures reaching over 30C, perhaps 33C in the southeast.
"In the shorter term some fine and warm weather over southern Britain for the next couple of days, but cloudier and wetter to the north."
He said temperatures will start to creep up this week hitting 26C (79F) on Friday in the southeast though cooler and showery in western parts.
The outlook for Glastonbury goers is for the odd shower in Somerset before a mainly dry and warm picture for the weekend.
Mr Brown added: "After a sunny start on Friday increasing cloud and a few showers will spread from the west during the afternoon, although not much rain is expected.
"Saturday will be fine with sunny spells and well broken cloud and temperatures up to 22C. "There will be a little light rain Saturday night and Sunday will be a cloudier day."
