After Friday morning's ceremony, the couple will travel by carriage to the palace and emerge onto the balcony for a precisely timed kiss - at 1:25 pm (8:25 am EDT) - followed by a ceremonial fly-past of military aircraft.

Then the partying starts. Some 650 people are invited to a luncheon with the queen, and later that night 300 close friends and family will attend a black-tie evening bash.

The palace says Queen Elizabeth II and her husband, Prince Philip, planned to go away for the evening, leaving the younger royals free to party unfettered - and Harry to make his best man's speech away from his octogenarian grandparents' ears.

British singer Ellie Goulding, 24, is reportedly going to perform, and rumors have it that Harry has even planned a breakfast for those with the stamina to dance all night.

Hundreds of thousands of people across the country will celebrate as well, for the day has been declared a public holiday. More than 5,500 official street parties are planned, including one by the anti-monarchist group Republic and another on Downing Street, home to Prime Minister David Cameron.

Cameron told CBS the wedding will bring "happiness and joy and light relief after some difficult times."them was also sung at the 1981 wedding of William's parents.

But as wedding excitement heated up, the weather in London cooled down. Royal wedding fans may want to pack extra umbrellas.

Gray skies were forecast for Friday, with a 30 percent chance of rain at the time of the ceremony, the Meteorological Office said. Some sunshine might break through in the morning, with temperatures rising to about 66 degrees.