Heavy and thundery showers could turn to torrential rain in some places, with parts of England, Scotland, Wales and Northern Ireland potentially seeing hail on Tuesday afternoon.
Localised flooding is a distinct possibility in the worst-hit areas as warm moist air from the continent meets a weather system coming in from the Atlantic.
The North East is expected to miss the worst of the conditions, but warnings are in place due to the erratic nature of the storms.
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Slow-moving thundery showers are expected to bring some localised torrential downpours of up to 20mm per hour across northern England and Scotland, with an attendant risk of surface water flooding and travel disruption.
As the week progresses, temperatures are expected to ease back to the teens - a level more typical of this time of year.
But, according to the Met Office, unsettled weather on Tuesday and slightly cooler temperatures the rest of the week don’t mean summer is done and dusted for another year.
A spokesperson for the Met Office said: “We have a yellow warning in place for heavy rain in many parts of the country tomorrow - but that doesn’t mean the end of summer.
“Temperatures are easing back to something more typical for this time of year as we return to a cyclonic pattern with systems from the Atlantic bringing more changeable conditions. The average for this time of year is 17 degrees - so still relatively warm.”
The yellow warning is in effect from 1pm to 9pm on Tuesday, so evening commuters could find themselves travelling as the weather hits.
“We could see some standing water as drainage systems struggle to keep up with the rain and some difficult driving conditions, so we advise motorists in affected regions to take it easy on the roads and allow extra time for their journeys,” added the Met Office.