SAN FRANCISCO (CBS SF) — A 12-kilometer foot race dubbed the world’s greatest costume race gets underway Sunday morning in San Francisco, according to race organizers.

Runners start the Bay to Breakers race at 8 a.m. at Howard and Main streets near San Francisco Bay and run west to The Great Highway and the Pacific Ocean breakers at Ocean Beach.

READ MORE: Bay Area Health Workers Cheer Newly-Approved 1-Shot Johnson & Johnson Vaccine

The race ends on The Great Highway just north of Lincoln Way.

The runners race up the Hayes Street Hill, one of the most notorious hills in all of racing, according to race organizers. The race also takes runners through Golden Gate Park.

Bay to Breakers is the oldest annual footrace in the world. It began in 1912.

National Weather Service forecaster Steve Anderson said temperatures will be in the 50s for the beginning of the race and rise to 60 to 65 degrees by afternoon.

Runners can expect low clouds, drizzle and fog at the start of the race.

“Summer-like weather in San Francisco,” Anderson said.

Last year 29,971 people finished the race. About 16,000 women finished and nearly 14,000 men.

Two Kenyans won the race last year. Isaac Mukundi Mwangi won the Men’s Elite Division and Jane Kibii had the fastest time overall among women.

San Francisco residents are being told to anticipate traffic delays on Sunday morning along the race route due to street closures.

READ MORE: Antioch Gas Station Shooting Leaves Man Suffering Life-Threatening Injuries

Some closures will be in effect until Sunday afternoon.

BART and Caltrain have added service to get runners to the starting line.

Caltrain will run four special northbound trains. The Special A train will depart the Palo Alto station at 6:12 a.m. and arrive in San Francisco at Fourth and King streets at 6:55 a.m.

The Special B train will leave San Jose’s Diridon station at 5:50 a.m. and arrive at the Fourth and King streets station at 7:04 a.m. The Special C train will depart the Diridon station at 6:04 a.m. and arrive at

Fourth and King streets at 7:21 a.m.

The Special D train will leave at 6:31 a.m. from San Jose’s Diridon station and arrive at Fourth and King streets at 7:55 a.m.

No alcohol is allowed on the special trains. San Francisco’s Municipal Railway T-Third line can take passengers to the starting line or runners can walk.

After the race, three express trains depart for Belmont at 1:10 p.m., 2:10 p.m. and 3:10 p.m. After Belmont, the trains will make regular weekend stops to the San Jose Diridon station.

BART will start operating at 6 a.m. with trains running at 20-minute intervals before 8 a.m.

BART officials are encouraging runners coming from the Peninsula to off-board at Montgomery station because of the number of people who attend the race. Runners from the East Bay are being encouraged to off-board at the Embarcadero station.

MORE NEWS: Hundreds Rally in San Mateo to Denounce Violence Against Asian Americans

Both stations are close to the starting line.