BOSTON -- The city of Boston stands to lose millions of dollars this weekend if severe weather hits on the 111th running of the Boston Marathon or sidelines Red Sox games and bogs down Patriot’s Day festivities.

If severe weather keeps crowds away and cancels Red Sox games, the economic loss could total nearly $15 million, according to officials at the Greater Boston Convention and Visitors Bureau.

The race, Sox games and holiday activites could generate approximately $97.7 million in economic benefits if the weather cooperates and people turn out for the marathon, bureau officials said.

CEO of the Greater Boston Convention and Visitors Bureau Pat Moscaritolo said the storm is a big cause for concern.

"It would be a huge hit, because once that money is lost it can’t be replaced,” he said. “It’s like an airline seat that doesn’t get sold, once the plane takes off, that revenue is lost forever.”

There are more than 23,000 official runners expected to be taking to the streets of Boston on Monday, including more that 3,250 runners from outside of the United States. According to the GBCVB runners and their families and guests will spend an estimated $50.7 million.

Moscaritolo said the financial loss from runners and their families who are already in the city would likely be minimal. They might even spend more, he said, because the potential bad weather keeps people indoors looking for entertainment.

The Boston Marathon is not the only event, however, that will have an impact of the city's bottom line. In addition to the spending impact of marathon weekend, there are four Red Sox games at Fenway Park, various Patriot’s Day activities in Boston and around Massachusetts, the John Hancock Sports and Fitness Expo at the Hynes Convention Center as well as the start of the spring tourism season.

The Red Sox games are expected to bring in close to $10 million. The start of the spring tourism season will reap $7 million for the region, and the John Hancock Sports and Fitness Expo is expected to rack up $5 million.

While BAA officials are saying that the marathon will continue as planned despite the predicted adverse weather conditions, the weather may have an impact on Patriots Day celebrations such as the annual re-enactment of the Battle of Lexington and the Red Sox games. Lexington said it will wait until Sunday to make a decision on its activities.

“If Sunday and Monday are bad, weather wise, there will be fewer people, 25 to 50 percent, lining the marathon route, and fewer people at the finish line in Copely Square, so there is a potential loss of $8 million,” Moscaritolo said.

“We could lose two Red Sox games due to the weather which is $5 million out the door, and another $3 to $4 million due to decreased spring visitors and canceled Patriots Day celebrations,” he said.