12-Week California International Marathon Training Plan

The 2026 California International Marathon is scheduled for December 6, 2026, so the 12-week window opens around September 13, 2026. Treat that as the outside edge of the window, then line week one up with the plan's normal weekly rhythm.

Use this window when your recent training is steady and the opening week will not be a mileage jump. If you are returning after a long break, twelve weeks is too little room to rebuild and peak at the same time. The course does not change the opening load you can handle, so choose from your current mileage and recent longest run before adding race-specific terrain.

Course-specific work starts early in a 12-week build. Put the race's terrain and expected conditions into long runs once the opening weeks feel controlled, without adding extra hard days. Train rolling terrain at steady effort. The single most CIM-specific skill is letting pace float on rollers while effort stays level; practice it on every long run with terrain. Add some sustained downhill running so the eccentric load of a net-descent race day is old news to your quads.

Do not double weeks or cram missed mileage into the remaining calendar. Use your current mileage, recent longest run, experience, goal, and available days to choose a plan that can enter at an appropriate point while preserving the taper.

Most Stride marathon plans run 12 to 20 weeks, and CIM's December date gives you a prime fall buildup. Get matched in the app and every week from today to Sacramento gets mapped, including long runs you can point at rolling terrain.

No, and that's the trap. It's net downhill from Folsom to the Capitol, but the first 20 miles roll constantly. Runners who race the descents early blow up on the flat final 10K. Steady effort over the rollers is the whole strategy.