The Haight Ashbury Street Fair will close streets including Haight, Ashbury, Clayton, Cole, Belvedere and Shrader in the Haight-Ashbury area from 6 a.m. to 8 p.m., according to the SFMTA.
In addition, the N Judah, 33 Stanyan, 43 Masonic, 37 Corbett and 71 Noriega lines will be affected by the street closures.
The triathlon will begin at 7:30 a.m. with a swim from Alcatraz to the St. Francis Yacht Club, followed by a bike ride through the Presidio to Great Highway and through Golden Gate Park, and a run from the Marina Green to Baker Beach and back.
Traffic will be affected throughout the route and Muni routes including the 18 46th Avenue, the 29 Sunset and the 38 Geary lines will be affected by the race.
For more information, go to www.sfmta.com.