It hasn't rained in London since Sunday, but it might on Kate Middleton's wedding day.
Gray skies are forecast for Friday, with a 30 percent chance of rain at the time of the ceremony, said Barry Gromett, senior press officer at The Meteorological Office.
Some sunshine is expected throughout the morning, with the temperature rising to about 66 degrees Fahrenheit (18 degrees Celsius), Gromett said. The average temperature for April 29 in the past few decades hovers at about 62 degrees.
Outside Westminster Abbey on Thursday, representatives from British gambling company Ladbrokes offered bets on whether it would rain, among other issues such as what hat Queen Elizabeth II would wear.
Ladbrokes' employee Alex Donohue, 21, wearing a top hat and Sunday-best suit, said rain wouldn't dampen anyone's spirits.
"People are here, they're in their tents, I've got my umbrella here myself. I don't think rain will put anyone off," he said.
Nicola Fairhurst, 33, one of many people camped in tents outside the church, had her umbrella ready. "It's a special day and rain won't make any difference," she said.
Though an estimated 2 billion people around the world will watch the wedding, tourist officials had no fears that rain would spoil their market.
"We've done research on the global perception on weather and we've found that foreign tourists don't mind British weather. It's not a barrier to the millions of tourists that come here every year," said Mark Di-Toro, spokesman for Visit Britain, the national tourist agency.