The wedding will begin at 11 a.m. on April 29, with the Archbishop of Canterbury presiding.
Following the ceremony, the newlyweds will travel from Westminster Abbey to Buckingham Palace by carriage in a procession. The route, which will likely be thronged by well-wishers regardless of the weather, will include Parliament Square, Whitehall, Horse Guards Parade and the Mall.
William and his bride are expected to emerge into public view briefly on the balcony at Buckingham Palace.
Queen Elizabeth II, William's grandmother, will then host a reception at the palace, followed by a dinner and dance hosted by Prince Charles.
But the big mystery remains as to who will be designing Middleton's gown.
It is also not clear who will provide the music, whether it will be icons like Paul McCartney and Elton John or a younger, dizzier crew that might appeal more to the newlyweds and their friends.
The Associated Press contributed to this story.