Diamond Jubilee weather: bring the brolly and be part of history, organisers plead Forecasters are predicting heavy rain all day, which could limit crowds for the Thames Jubilee Pageant and cause the cancellation of some of the 10,000 street parties planned throughout the country. The 1,000-boat flotilla on the Thames tomorrow has taken two years to plan and cost £12 million in private donations, with organisers hoping more than one million people would attend. Lord Salisbury, chairman of the Thames Diamond Jubilee Foundation, urged the nation to celebrate whatever the weather. He said: "This is an event that celebrates Britishness, and coping with the rain is something quintessentially British. Indeed, people with long memories will recall that it rained on the day of the Coronation 60 years ago. The Met Office has forecast heavy showers in London throughout Sunday, with temperatures as low as 50F (10C), though a steady breeze will mean it will feel even colder, around 46F (8C). "Sunday is going to be the worst day of the weekend," said Tom Morgan, a Met Office forecaster. It will be a wet morning, quite breezy, and while the rain may ease a little in the afternoon it will still be quite damp. A brisk breeze will make it feel pretty chilly. More rain is forecast for Monday ahead of an open-air concert at Buckingham Palace. On Tuesday, showers will probably hit London just as the Royal family are taking part in a carriage procession, the Met Office said. Michael Lockett, chief executive of the Thames Diamond Jubilee Foundation, said the rain should not stop the nation taking the chance to "be part of history." He said: "In these austere times, we need cheering up more than ever. Tomorrow will be a great boost to all of our spirits.