The Royal Wedding could be damp, according to the latest weather forecasts, but showers would also mean the return of the Glass Coach used during the wedding of Charles and Diana.

CBC meteorologist Johanna Wagstaffe said the forecast for Friday in London includes a high of 17 C and a 40 per cent chance of isolated showers — a marked contrast from recent weather in the city, which has been enjoying sunny skies and the warmest April on record.

Some forecasters have even called for heavy rains or thunder.

There are two coaches that could be used to carry Prince William and Kate Middleton from Westminster Abbey to Buckingham Palace. If it rains, it will be the Glass Coach used in the wedding of William's parents, Charles and Diana, in 1981.

The Glass Coach, built for the Lord Mayor of London in 1881, was bought by the royals 30 years later for King George V's coronation. The carriage, which has large windows, has been used by five royal brides, including Sarah Ferguson in 1986, now-Queen Elizabeth in 1947, and her mother, Elizabeth, in 1923.  

If the weather is fair, William and Kate will travel in the open-topped 1902 State Landau, which was built for King Edward VII's coronation.