Britain is set to enjoy the hottest day of the year - while Europe swelters in heat of more than 100F (37.7C).
June 30 is forecast to be the hottest day of the year so far - as southern Europe prepares for a sizzling heatwave.
Millions of sun-seekers heading for Spain, Italy and France are being warned to get ready for very hot conditions.
Temperatures there are expected to break through the 100F barrier in the next couple of weeks.
They could go as high as 44F in southern Spain (111.2C), just as holiday Brits arrive for the traditional summer breaks.
According to forecasters, Britain may also have a 'mini heatwave' at the end of July.
Leon Brown, chief meteorologist with the Weather Channel, said Tuesday is likely to be the hottest day of the year, hitting 28-30 C.
He went on: "That is likely to be in the south east of the country, and especially East Anglia.
"Southern Europe is heading for a heat wave and it could get up to 42-44F (111.2C) in southern Spain, which is too hot really.
"Once you get into late 30s C, it is uncomfortable for most people, you need air con and it is too hot go outdoors in the afternoons.
"There is real low pressure in Spain, some of Italy and southern France and that will bring a plume of heat to the south east of the UK.
"But that is only likely to last for the day on Tuesday, and then the rest of the week becomes cooler and fresher."
He added: "It could come down nicely to the mid 20s C after that.
"Wimbledon's first week looks reasonably settled and Glastonbury also looks quite nice - there will be a little bit of rain on the Friday and the Sunday, but we will not have the muddy quagmires that there have been before."
A heatwave in Pakistan has killed more than 450 people, while the southern states of America are also experiencing temperatures of more than 100F, with extreme weather and tornadoes in the mid West.
The record British temperature is 37.1C (98.8F), recorded at Cheltenham in August 1990. In 1976, when the country basked in 15 consecutive days at 32C (90F) and above, and 1995 were two of the hottest summers on record.