Rain and severe traffic congestion will blight the Bank Holiday weekend across much of Britain.

The RAC is predicting the “worst ever” congestion for the May Day Bank Holiday as millions of drivers hit the motorways and many head for the coast.

Weather forecasters are warning that cool, wet weather will sweep across Britain tomorrow and Bank Holiday Monday.

According to the Met Office, today will have the best of the weather for barbecues and beaches. It will be bright and quite warm for many southern and eastern areas, but become wet and windy in the North West later in the day. The wet weather will then move south tomorrow and Monday, with showers in most areas.

Elizabeth Anetts, a forecaster from MeteoGroup, a weather forecasting company, said: “Saturday looks like it will be the best day for most places.

“It will be quite cloudy to start off with but that will burn off in most parts by the afternoon.

“There will be sunny spells in most parts and temperatures will be warm but it won’t be a scorcher. In London, it should reach about 20C (68F) and elsewhere between 16C (61F) and 19C (66F).”

A Met Office spokesman added: “By Sunday it will be more unsettled, cool and windy at times with rain or showers for most, although sheltered eastern areas may be dry for much of the time.”

The AA expects an extra 20 per cent of cars on UK motorways and 18 million vehicles on the roads in total. Bank Holiday Monday is likely to be the busiest day with people returning home from day trips and weekends away.

It also predicted that Alton Towers theme park in Stafford-shire and Longleat in Somerset would be the leading tourist attractions. The organisation expects that it will attend 51,000 breakdowns.

An RAC spokesman said: “The UK is likely to see the most congested roads ever over a May Day weekend due to a packed events schedule, pleasant memories of the hot Easter break and good weather forecasts for Saturday. Motorists should check the latest travel news online and allow plenty of extra time for journeys.” Thousands of Britons are

150% also expected to head abroad and Heathrow expects almost 800,000 passengers to pass through its doors.

The most popular destinations are New York, Amster-dam, Paris, Dublin, Los Angeles, Edinburgh, Dubai, Hong Kong, Frankfurt and Chicago, a spokeswoman said.

Last month’s sizzling spell of weather was the warmest April since records began in 1659. The previous highest average, set in 1865, was smashed as temperatures soared throughout the UK. The month’s final average figure of 11.2C (52.16F), which takes into account daytime and nighttime readings, obliterated the 1865 mark of 10.6C (51.08F).

Last month was the third sunniest April on record, behind 1984 and 1893, and the fifth driest in the last 100 years.

The unseasonal hot spell looks likely to lead to 2007 becoming the warmest year on record — a year after 2006 claimed the title.

Look out for . . .

Beware usual traffic hotspots — the M25, M1 through Nottinghamshire and the M6, particularly around Birmingham

Fine weather today could create coastal route misery, particularly: A12 to east coast; M3, A21, A23 and A3 to south coast; M5 Bristol to Weston-Super-Mare; A55 to coast of North Wales; A64 to Scarborough

Events add to the problem. Historic Commercial Vehicle Society London-Brighton Run tomorrow — expect problems on the M23; Newmarket race meetings on Saturday and Sunday — A142, A14 and A11 likely to be congested; motor racing and motorbike events at Silverstone (A43), and Oulton Park (A54 and A49)

Weather today will have a grey start for many but cloud will thin and break to give warm sunny spells for most by afternoon. It will become cloudy and windy in the far North West with rain arriving later. Sunday and Monday will be more unsettled, cool and windy at times with rain or showers for most

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