More than 20,000 runners, walkers and wheelchair racers joined early Sunday in the kickoff of the 29th annual Los Angeles Marathon -- a 26.2-mile course that runs from downtown to the ocean.
The marathon officially began at 7:10 a.m. under clear skies at Dodger Stadium, with the women elite runners starting first, followed by the elite men and the full field.
Street closures will run throughout downtown, Hollywood, Beverly Hills and Santa Monica and will remain in place for at least three hours. Some of the major closures include portions of Sunset, Hollywood and Santa Monica boulevards. The race ends in Santa Monica.
The temperature around race time Sunday in downtown L.A. was in the low 60s but is expected to heat up into the low 80s later in the day.
"It should be a pretty nice day — warm, it'll be warm by the afternoon," said Scott Sukup of the National Weather Service.
To ward off congestion and commuter frustration, marathon officials have issued a course closure grid, a map of additional streets that will be closed Sunday and various other maps and tools to navigate across the county that morning.
Crossing the course will not be permitted. Streets will reopen on a rolling basis as approved by public safety officials.
Freeways around Los Angeles County mostly will be unaffected by the closures, save for some ramps that will be shut down for several hours.
Officials in West Hollywood and other cities along the route are also sending out advisories to residents regarding street closures, and suggesting the public follow local official Twitter accounts for announcements as streets reopen.
There is also a map on Commuterama.com that is designed to help motorists avoid the closures and let those who want to cheer on the marathoners know how they can navigate the route.