Forecasters warned of torrential downpours tomorrow for the first day of the bank holiday weekend.
The pop festivals in Reading and Leeds are among locations at risk of a soaking with up to an inch of rain predicted in some places.
Big queues built up around Shrewsbury and Telford and across the Midlands motorway network as the getaway started last night.
Andy Ratcliffe, a forecaster with MeteoGroup, said: “There are going to be widespread and frequent heavy showers and thunderstorms, with torrential rain in some places.
“We are looking at 5-15mm (0.6in) generally over the 24 hours from midnight, and perhaps locally up to 25mm (0.98in) in some areas. If there are torrential downpours, with a lot of rain falling in a short space of time, there could be local flooding.”
Today saw rain in the south west from early this morning, which spread to other parts of England.
After tomorrow’s heavy rain, Sunday is looking drier, though with a risk of showers in northern and eastern areas, before rain returns from the west early on Monday. Temperatures are not expected to reach much higher than 20C (68F) over the weekend – a stark contrast with last weekend when the thermometer touched 32C (90F).
Around 1.8 million Britons are heading off abroad for the break. Travel organisation Abta said Spain and its islands were the most popular destinations.