The marathon starts at 5:30 a.m. and the half marathon begins at 6:15 a.m. Both races begin at Fashion Island, near the Newport Beach Marriott Hotel & Spa. Both races end at the OC Fair and Events Center.
Thousands of spectators are expected to line the course and the start line in front of the Newport Beach Marriott.
They'll be watching some avid runners and even some who are trying to reach an elite level.
The OC Marathon can be used as a qualifier for any marathon in the country, including the Boston Marathon.
The runners will have a picturesque backdrop while competing in the OC Marathon.
"I think we have one of the most beautiful courses, the half marathon wrapping around Fashion Island and going through Corona del Mar, and continuing up on the bluff overlooking the back bay and finishing at the OC Fair, it has a fantastic finish," said Gary Kutscher, the OC Marathon race director.
The course runs through four different cities: Newport Beach, Irvine, Santa Ana and Costa Mesa. Road closures have been set and police have advised residents to avoid Newport-Mesa areas, which will be affected by the marathon between 5 a.m. and noon Sunday. Detailed information can be found at http://www.ocmarathon.com.
"There are a few different road closures from last year," Kutscher said. "It is mostly in Santa Ana on Raitt Street. Residents at first were showing concern, but we were able to figure out a way get traffic going smoothly."
He added that more people know about the marathon. They have been managing a lot of calls and figuring out solutions for the interested runners.
He also said OC Marathon has partnered with the Long Beach Marathon and Surf City Marathon to create the Beach City Challenge.
"This consists of signing up and completing all three races and you get a very special medal at the end," he said.
The Kids Run the OC one-mile event takes place Saturday morning at the OC Fair and Event Center in Costa Mesa. The Kids Run the OC obesity prevention program, which has registration closed, set a record with 4,075 participants via 67 schools.
Kutscher said Greenville Elementary had the most kids in the Kids Run the OC program with 379 kids registered to run.