The Bank Holiday weekend will see up to 15 million cars taking to the nation's roads, sparking fears of heavy traffic and delays.
However, in sharp contrast to last weekend's hot conditions, travellers face cool, showery weather.
People using trains will have to contend with delays and cancellations on some lines due to engineering work, while a number of Tube lines have also been part-suspended.
The Highways Agency has suspended more than 30 sets of roadworks until Monday, but 32 remain in place, including those on a section of the M25 in Hertfordshire.
Forecaster Tom Tobler, from MeteoGroup, the weather division of the Press Association, said most parts of the UK will see some rain - with temperatures plummeting after last weekend's hot conditions.
He said a deep area of low pressure would bring in cool, breezy and showery weather, with highs of 16C (61F) in the south.
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