20-Week California International Marathon Training Plan

The 2026 California International Marathon is scheduled for December 6, 2026, so the 20-week window opens around July 19, 2026. Treat that as the outside edge of the window, then line week one up with the plan's normal weekly rhythm.

Use the longer window to make the early build calmer, not to add five months of hard training. The plan should begin close to your current load, hold most running easy, and delay the biggest race-specific work until the middle of the cycle. 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.

Build general durability first. Add the race's hills, flat sustained running, downhill exposure, heat, or humidity in layers after the weekly rhythm is stable, then make the final long runs the most course-specific. 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.