Race-day weather · Wyndo for runners
San Antonio Marathon weather
December 6, 2026 · San Antonio, TX · scheduled start 7:15 AM (America/Chicago). What the start usually feels like, year by year — and a live start-time read once the race is inside the 7-day forecast window.
Countdown
102 days to race day
The live race-day forecast unlocks 96 days from now, when December 6, 2026 enters the 7-day forecast window — a start-time read for the scheduled 7:15 AM start. Until then, live hourly data is not available; the history below shows what race morning usually looks like.
Typical start temp
51°F
median of 20 years
A warm year
56°F
75th percentile start temp
Rain at the start
15%
3 of 20 measured years
Race-morning weather history
Early December in South Texas is mild but unusually variable (means: high 66F/low 44F); the 2025 inaugural ran warm at a 74F high. Only one edition has been held — deeper history shown for this slot is start-line climatology, not past editions of this race. Wyndo tracks what this calendar slot has actually served up at the start hour — temperature, dew point, wind, and rain — including the years when weather canceled or disrupted the race, and reads the live forecast for the start once race week arrives.
Median start temp
51°F
p75 (a warm year): 56°F
Median dew point
46°F
at the start hour
Rain at the start
15%
3 of 20 measured years
Warmest start
69°F
in 2007
Scroll sideways to see all columns.
| Year | Start temp | Dew point | Wind | Precip (start hr) | Day's high |
|---|---|---|---|---|---|
| 2025 | 56°F | 56°F | 5 mph | dry | 75°F |
| 2024 | 51°F | 46°F | 3 mph | dry | 70°F |
| 2023 | 46°F | 36°F | 5 mph | dry | 73°F |
| 2022 | 56°F | 46°F | 6 mph | dry | 58°F |
| 2021 | 67°F | 65°F | 9 mph | dry | 78°F |
| 2020 | 40°F | 34°F | 7 mph | dry | 68°F |
| 2019 | 51°F | 24°F | 9 mph | dry | 67°F |
| 2018 | 50°F | 36°F | 5 mph | dry | 74°F |
| 2017 | 65°F | 64°F | 3 mph | 0.4 mm | 76°F |
| 2016 | 51°F | 50°F | 10 mph | 0.8 mm | 52°F |
| 2015 | 44°F | 42°F | 3 mph | dry | 71°F |
| 2014 | 52°F | 50°F | 8 mph | dry | 61°F |
| 2013 | 56°F | 54°F | 5 mph | dry | 71°F |
| 2012 | 69°F | 66°F | 8 mph | dry | 81°F |
| 2011 | 62°F | 61°F | 12 mph | 0.6 mm | 67°F |
| 2010 | 47°F | 26°F | 14 mph | dry | 61°F |
| 2009 | 41°F | 36°F | 2 mph | dry | 59°F |
| 2008 | 37°F | 27°F | 5 mph | dry | 71°F |
| 2007 | 69°F | 68°F | 6 mph | dry | 80°F |
| 2006 | 44°F | 29°F | 11 mph | dry | 50°F |
Slot climatology: each row is the weather at this race's usual calendar slot and start hour (ERA5 reanalysis at the start line) — including years when the edition was canceled or moved. A computed slot date is not a claim the race ran that day.
Your heat-adjusted goal for the marathon
The same cited model as the full calculator, pointed at this race: the median start-hour conditions this calendar slot has served up — climatology, not a forecast.
Your race-day brief
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Race facts
- Start line
- CAVEAT — the 2026 start line is officially unpublished (FAQ: 'Start Line: TBD') and the official courses page contradicts it with Hemisfair. Coordinates are the VERIFIED 2025 start: Dolorosa St at Main Plaza, downtown (official 2025 info sheet). Hemisfair (29.4199, -98.4841) is ~1 km southeast and is the confirmed FINISH both years. Re-verify when the Race Week Runner Guide publishes.
- Scheduled start
- 7:15 AM (America/Chicago) — Official 2026 course pages: marathon and half both 7:15 AM CT Sun Dec 6; 5K Friday Dec 4, 8:00 PM (night race) at Hemisfair. 7:15 is the FIRST corral release — corrals by estimated finish time at 1-2 min intervals. No wheelchair/elite gun published. Course limits 7:00/4:00 from each runner's start crossing.
- Field size
- Marathon finishers, 2025 inaugural edition, per FindMyMarathon (aggregator). The quoted 'over 18,000 participants' was a pre-race weekend-wide estimate across all three races — do not substitute. One edition only; no trend.
- Registration
- open (RunSignup, tiered; 2026 marathon $189, half $149, 5K $59; 2025 inaugural sold out)
Wyndo is not affiliated with or endorsed by the San Antonio Marathon (officially the "San Antonio Marathon") or its organizers. Race names are used descriptively to identify the event; schedules and start times belong to the race — always confirm details on the official site. Weather guidance here is informational, never medical advice, and event alert flags on race day belong to the race's own medical team.