The California International Marathon is Sunday. Here are the roads to avoid (and spots to watch)

A record level of participation in the California International Marathon on Sunday, Dec. 2, will mean fewer gaps in the field for a race that blocks traffic from Folsom to downtown Sacramento.

Monitors may allow traffic to cross the course, but only if there are large gaps between runners. The more runners, the fewer gaps. Motorists should plan to avoid the course during the race.

More than 13,000 runners registered this year for the marathon’s 36th anniversary, and another 7,500 registered for its relay event, the 5K and the Kid’s FunRun scheduled for downtown Sacramento on Saturday. About 11,000 runners registered for the marathon in 2017.

The CIM’s start area in Folsom is closed to spectators. There is no non-official vehicle access near the course start on Auburn-Folsom Road near Folsom Dam, and parking is limited. Street closures in the area begin at 5:20 a.m. Sunday and end at 9 a.m. The race starts at 7 a.m.

The race concludes at the state Capitol. Roads in the downtown area will start closing at 2 p.m. on Friday, beginning with Capitol Mall between 8th and 10th streets. Some closures around the finish will be in effect until 5 p.m. Sunday.

The weekend weather forecast from the National Weather Service projects showers on Friday and Saturday, followed by a mostly sunny Sunday with a high of 51 degrees in downtown Sacramento. Temperatures at the start in Folsom could be in the low- to mid-30s.

The slightly downhill course, which drops 340 feet in elevation over its length, is known as a place to run a fast time to qualify for the Boston Marathon. The CIM is put on by the Sacramento Running Association.

Suggested viewing areas on the race route

2018 California International Marathon route map