Remnants of Tropical Storm Dexter will bring an increase in temperatures over the weekend, with highs of 34C possible next week.
A heatwave could be registered in parts of the South early next week and could spread more widely if temperatures hold.
Temperatures of 28C (82F) are possible in the South on Sunday, reaching 30C (86F) across parts of England on Monday before getting closer to 34C (93F) on Tuesday.
Warm and muggy nights are to be expected, especially in the South.
Conditions will be more unsettled in the North, with strong winds and rain at times.
In its forecast the Met Office said Friday will be a brighter day for many, with sunny spells across southern and central areas and highs of 25-26C expected. Northern Scotland will be breezy with showery outbreaks of rain.
Saturday will also see sunny spells for much of England and Wales, but there will be some rain in northern areas, paritcularly northern Scotland.
A weather front moving in from the west will bring rain to Northern Ireland, parts of Scotland and possibly northern England by Sunday evening, while central and southern areas are expected to remain dry with sunny spells.
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Temperatures will begin to rise in the South from Sunday evening, as the remnants of Tropical Storm Dexter “draws warm air up from the southwest across the UK”, the Met Office said.
Temperatures are expected to exceed 30C across parts of central, southern and eastern England on Monday and Tuesday, the forecaster added.
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“We’re confident that temperatures will increase markedly by the start of next week, reaching the low 30s Celsius in parts of England on Monday and perhaps the mid 30s in a few places on Tuesday,” said Met Office deputy chief meteorologist Steven Keates.
“However, the length of this warm spell is still uncertain, and it is possible that high temperatures could persist further into next week, particularly in the south.”
“Ex-Dexter sets the wheels in motion for an uptick in temperatures, but the weather patterns then maintaining any hot weather are rather more uncertain”.
