Net Downhill, BQ-Friendly, and Growing: California International Marathon Has the Numbers to Back Its Reputation

Running point-to-point from Folsom to Sacramento, CIM drops 333 feet over 26.2 miles on a course that consistently delivers fast times — the 2025 field posted a median finish of 4:10:29, and the top quarter came in under 3:40:32. With cold, calm December mornings as the norm and a net-downhill profile doing real work from the opening miles, this is a race built for runners chasing a personal best or a Boston qualifier.

By the numbers

The field has grown meaningfully in the editions on record, rising from 370 finishers in 2024 to 450 in 2025 — a 22% jump that the race billed as record participation. Median times improved slightly year over year, from 4:12:42 to 4:10:29, a modest but consistent signal that the field is either getting faster or benefiting from better conditions. The 75th-percentile mark held nearly flat at around 4:45, suggesting the back of the field is stable even as the middle tightens.

How the course runs

The course descends steadily from Folsom, with the most consequential drops coming early — 101 feet between miles 2.2 and 3.8 and a longer, gentler 116-foot descent running from mile 15.1 to 21.8. The final miles into Sacramento are essentially flat. The overall shape is downhill, and runners feel that from the start.

The 2025 fade curve tells a clear story: the field opens conservatively, finds its rhythm through the middle miles, then slows predictably in the final third.

The fastest segment in 2025 was the stretch around the half, at 9:02/mi, with the field gradually losing pace through miles 21–25 before recovering slightly to the line.

Pacing patterns

Back-half slowdown is standard across marathon fields, and CIM is no exception. In 2025, 57% of finishers ran a positive split, with an average second-half slowdown of 6.1% — noticeably better than 2024's 9.1% slowdown, when 65% of the field went out too fast relative to what they could sustain. The 2024 conditions — warmer at 49–59°F with lower humidity — may have encouraged more aggressive early pacing that the back half couldn't absorb. The cooler, damper 2025 morning (36–46°F, 86% humidity) appears to have produced more disciplined early miles. Either way, the long descent from miles 15 to 22 rewards runners who arrive at that section with legs still under them.

The weather question

CIM's December slot in Northern California reliably delivers cold mornings. In 2025 that meant 36–46°F, overcast, with wind around 3 mph; in 2024 it was a warmer 49–59°F with scattered clouds. For 2026, the forecast sits at 38–48°F, misty, ~43°F at the start, with wind around 8 mph and 93% humidity. That's closer to 2025 conditions than 2024 — cold and damp, with slightly more wind. Based on the two prior editions, cold-and-calm mornings have correlated with better collective pacing and a smaller average slowdown. The added wind in 2026 is a variable worth tracking, particularly on the more exposed stretches in the back half.

What it takes

In 2025, breaking into the top 10% required finishing under 3:12:49; the top quarter came in under 3:40:32. The median sat at 4:10:29. For Boston qualifiers, the sub-3:40 threshold is well within reach for the top quarter of the field, and the net-downhill profile makes this one of the more favorable courses on the West Coast for that purpose.

What to watch

The field grew 22% in a single year — whether that trajectory continues toward 500-plus finishers in 2026 will say something about CIM's rising profile. The 2025-to-2024 improvement in collective pacing (average slowdown dropping from 9.1% to 6.1%) is a trend worth watching: if the 2026 weather holds close to 2025's, another well-paced field is plausible. And with the forecast again favoring cold, low-wind conditions, the conditions for a strong BQ showing are in place — how many runners convert that opportunity is the question the finish line will answer.