Furnace Friday could see temperatures of 30C in Portsmouth and South East
The heatwave is gearing up for round two after more comfortable temperatures this week - but only in some parts of the UK.
The mercury could climb back up to 31C in London and the South East this weekend the Met Office has said, with sunshine returning to most of the country.
But while London is set to sizzle again the North of England, Scotland and Northern Ireland will enjoy temperatures in the mid-20s, with scatterings of rain.
A spokesman for the Met Office told the Press Association: '˜Essentially at the end of the week we're looking at a bit of a north-west/south-east split in the weather.
'˜Northern and some western areas will often be cooler with some outbreaks of rain - particularly in Northern Ireland and that could spread in to the south and western Scotland.'
On Friday, temperatures are likely to hit at least 29C and possibly 30C in southern parts of the UK he said, with temperatures elsewhere sitting at around 24C to 25C.
The spokesman said: '˜Temperatures will continue to build, but nothing quite as hot as what we saw towards the end of last week.'
He continued: '˜This weekend is much more promising than last weekend - plenty of sunshine around although the north of England could see a few showers on Saturday.'
The heat is likely to continue into next week.
'˜Temperatures will remain pretty hot across at least the south of England but potentially more widely across the UK - we could see some wet weather coming across the north west, but still pretty hot,'Â the spokesman said.
Holidaymakers heading to Spain and Portugal were warned of an extreme heatwave which could see the hottest-ever temperatures recorded in continental Europe.
Luke Miall, a Met Office meteorologist, said the current record of 48C (118F) in Athens, Greece, in 1977 could be broken as wave of blisteringly hot air sweeps in from Africa.
Temperatures crept into the low 40s on Wednesday and are expected to rise and peak at the weekend, with the highs expected inland rather than in coastal areas.
He added: '˜These sorts of temperatures are not only exceptional for the locals but people from the UK will never really have experienced them.
'˜Especially with it being the school holidays, and the very young and old being susceptible to heatstroke, we're advising tourists to keep out of the midday sun and protect themselves.
'˜Combined with high pressure in charge, blue skies every day, and the ground already warmed up, that leads to a day-on-day build, combining to give us these intense temperatures.'
Temperatures in south-west France could also rise to the high 30s, he added.