Summer is set to get into full swing this weekend as parts of Britain bathe in temperatures surpassing the Mediterranean.
However, gathering storm clouds threaten a washout for some on Saturday.
The mercury is expected to climb up to 26C (78F) on Sunday, around 10C (50F) higher than the monthly average, as a current of warm air carried from the continent continues to flow in under sunny skies.
But as the South East enjoys temperatures higher than Seville and Sardinia, the western edge of the United Kingdom faces torrential downpours that could see a week's rain fall in an hour.
The Met Office advised those in Wales, the Midlands and south Pennines to be on the lookout for weather warnings as sharp thundery spells could dump up to 20mm on some parts on Saturday.
Meanwhile, light winds mean pollution levels are expected to creep upwards over the weekend.
Met Office forecaster Charles Powell explained: "We are going to have a bit of an east-west divide on Saturday, the further east you are the drier it will be and the further west the higher the risk of thunder storms.
"Sunday will be better with a warmer day for all and temperatures of up to 26C in and around London and 20-23C in western parts.
"A low pressure area to the south of the UK and higher pressure over Scandinavia means we are seeing this south easterly air flow. Paired with breaks in the cloud it means we get this dry, fine weather."
Previous concerns the European air current was sweeping in dangerous levels of pollution may have been over-blown, although those with respiratory health problems are advised to be aware that pollen levels and some pollutants could be higher thanks to local pollution.
Mr Powell continued: "A lot of people have been mentioning the smog word, although there is no smoke and no fog.
"Pollutant levels may go up as you would naturally expect with long dry periods, as it gets a bit murky when there's not enough wind to mix things up."
The Department for Environment Food & Rural Affairs (Defra) said there will be areas of moderate air pollution across England and Wales on Friday with low levels across Scotland an Northern Ireland.
On Saturday, pockets of high air pollution are possible, with large areas of moderate air pollution across England and Wales. Levels are expected to remain low across Scotland and Northern Ireland.
Pollution levels are expected to peak on Sunday, with high levels possible locally and widespread moderate air pollution
Those heading outdoors to enjoy the fine weather over the weekend are also warned to be aware that UV levels will be high.