Jubilee revellers heading to London to watch the one of the largest flotillas ever assembled on the River Thames should brace themselves for wet weather.
Royal watchers will be huddling under umbrellas rather than basking in glorious sunshine as 1,000 boats sail down the river to mark the Queen's 60th year on the throne.
Andy Ratcliff, a forecaster at MeteoGroup, the weather division of the Press Association, said: "London will see rain at times and there could be the odd heavy burst. It will be a chilly day so people should dress accordingly.
"We will probably see a high of 11C (51.8F) so the advice is to take wet weather gear and be prepared for pulses of rain. It will not be the sunny day people may have hoped for."
Those seeking a long weekend in the sun would be better off heading for the South Coast, which should remain dry with highs of 18C (64.4F).
Street parties in the East and West of the country will be blighted with rain, which will be heaviest in Wales and western parts of the Midlands.
In Scotland there will be sunshine but with a fair amount of cloud in eastern areas, Mr Ratcliff said.
It is expected to remain cloudy in Northern Ireland.