Britain could be baking in over 30C by the middle of the week ahead of a bank holiday heatwave, according to the Met Office.
Temperatures are set to soar once again in the coming days and had originally been forecasted to peak over next weekend.
But the national weather agency is now predicting the mercury may well exceed expectations on Wednesday in "one or two spots" across the south and east.
In a tweet this afternoon, the Met Office said: "Temperatures generally near average today, but gently rising during the coming days reaching a peak midweek
"Temperatures could locally exceed 30°C in one or two spots across the south and east on Wednesday."
The UK has seen an unsettled period of heavy rain and thunderstorms in recent days, having recorded its highest ever temperatures in excess of 40C last month.
Last week torrential rain led to flash floods.
And while the up and down weather will likely continue, the mercury will quickly build into what could be another prolonged period of higher than average temperatures.
Further rain is, however, forecast in parts, with Britain still stricken by drought and hosepipe bans.
The last couple of months have been so dry that stressed trees are beginning to shed their leaves in what experts have called a 'false autumn'.
Showers will arrive in the far south of England and north west of Scotland next weekend, despite what is largely expected to be a fine and dry period.
Met Office operational meteorologist Dan Stroud told the Mail Online : "It's a messy picture this week."
He said the weather will be "rather changeable" and is set to begin cloudy with rain across the country.
But the temperatures and humidity, particularly in the south, will be rising into Wednesday.
Levels are then expected to drop off towards the end of the week before rocketing up again.
Mr Stroud said a heatwave over the weekend is a possibility.
"Locally, there will be very warm temperatures," he explained.
"So the devil is in the details. [The heatwave question is] one to answer closer to the time."
He added it is difficult to tell if this would be the UK's last stint of warm weather before the autumn, though the Met Office long range forecast does suggest early September could still be reasonably fine and dry.
It has been the driest summer since 1976, with 35 million Brits to be under hosepipe bans by the end of August and 30.7 million suffering through a drought.
