Folsom Dam to the State Capitol, net downhill, and the most popular Boston qualifier in the country. Early December is usually cool and calm, with the occasional soaking Pacific storm.
By Brett Heimlich, part-time runner.
Plan for about 43°F (6°C) at the 07:00 start, feeling like 39°F (4°C), with 94% humidity and 5 mph wind, warming to roughly 53°F (12°C) by the finish. It rained on 3 of the last 10 race days. Wear: Long Sleeve Tech Shirt, Running Tights, Running Cap, Waterproof Jacket.
43°F (6°C)
53°F (12°C)
3 of 10 years
38° to 52°F
Advertisement
Conditions at the 07:00 start on the race's usual date each year (first Sunday of December). Years when the race was cancelled or moved still show that date's weather. Source: Open-Meteo ERA5 archive.
| Year | Start temp | Feels like | Finish | Humidity | Wind | Rain | Sky |
|---|---|---|---|---|---|---|---|
| 2025 | 40°F (4°C) | 37°F | 43°F | 100% | 2 mph | – | Overcast |
| 2024 | 41°F (5°C) | 37°F | 51°F | 95% | 4 mph | – | Overcast |
| 2023 | 51°F (11°C) | 48°F | 62°F | 92% | 6 mph | – | Overcast |
| 2022 | 45°F (7°C) | 42°F | 54°F | 94% | 4 mph | 0.39 in | Mostly clear |
| 2021 | 45°F (7°C) | 43°F | 50°F | 98% | 2 mph | – | Overcast |
| 2020 | 40°F (4°C) | 35°F | 56°F | 94% | 5 mph | – | Mostly clear |
| 2019 | 52°F (11°C) | 46°F | 54°F | 87% | 13 mph | 1.35 in | Drizzle |
| 2018 | 38°F (3°C) | 34°F | 51°F | 98% | 3 mph | – | Clear |
| 2017 | 41°F (5°C) | 35°F | 53°F | 88% | 7 mph | 0.07 in | Clear |
| 2016 | 38°F (3°C) | 34°F | 53°F | 93% | 1 mph | – | Overcast |
Coldest start: 38°F (3°C) in 2018. Warmest: 52°F (11°C) in 2019. Wettest: 1.35 in in 2019.
Built from the 10-year average start conditions by the same engine as the live tool. Treat optional items as corral-only layers you can shed.
Long Sleeve Tech Shirt
Breathable moisture-wicking fabric
Waterproof Jacket
Breathable rain protection
Running Tights
Full-length compression tights
Light Gloves
Thin running gloves
Headband
Ear coverage without overheating
Running Cap
Keep rain out of eyes
Trail or Waterproof Shoes
Better grip and water resistance
Wool Running Socks
Warm and moisture-wicking
✓ Worn by the author
Grid-fleece quarter zip for 25 to 40°F starts
$128
✓ Worn by the author
Compression tight for 40 to 55°F, works under shorts
$78
Touchscreen-compatible, windproof, and packable
$55
Warm, itch-free merino blend for cold runs
$38
✓ Worn by the author
Thin, ribbed quarter sock that keeps grit out
$36
As an Amazon Associate, we earn from qualifying purchases. Some links may earn a commission at no extra cost to you.
Over 2016 to 2025 the start averaged 43°F (6°C) (feels like 39°F (4°C)) with 94% humidity and 5 mph wind, warming to about 53°F (12°C) by the finish. It rained measurably on 3 of those 10 race days. The coldest start was 38°F (3°C) in 2018; the warmest was 52°F (11°C) in 2019.
For a typical 43°F (6°C) start: Long Sleeve Tech Shirt, Running Tights, Running Cap, Waterproof Jacket. Dress for about 15°F warmer than the start temperature, since the race itself adds that much, and plan to shed anything you only need in the corral.
The California International Marathon is usually held on first Sunday of December. The next expected date is Sunday, December 6, 2026. Confirm on the official site, since dates occasionally move.
The live forecast on this page comes from Open-Meteo and unlocks 16 days before the race. Forecasts inside 7 days are reliable for temperature within a few degrees; rain timing firms up in the last 2 to 3 days. Until then, the 10-year history above is the best planning guide.
Get a what-to-wear call for the live forecast at your exact location, free, no signup.
Check your live running weatherAdvertisement