Race-day weather · Wyndo for runners
Bay to Breakers weather
May 16, 2027 · San Francisco, CA · traditional start around 8:00 AM (America/Los_Angeles) — not yet confirmed for 2027. What the start usually feels like, year by year — and a live start-time read once the race confirms its schedule and race week arrives.
Countdown
261 days to race day
The live race-day forecast unlocks 255 days from now, when May 16, 2027 enters the 7-day forecast window. Until then, live hourly data is not available; the history below shows what race morning usually looks like.
The 2027 start time hasn't been published yet — the 8:00 AM start shown here is carried from a previous edition. We'll switch on the live start-time read when the race posts its schedule.
Typical start temp
56°F
median of 20 years
A warm year
59°F
75th percentile start temp
Rain at the start
15%
3 of 20 measured years
Race-morning weather history
Typical mid-May SF mornings: cool, often foggy/overcast near the coast (50s F), breezy toward Ocean Beach; typical-climate characterization, UNVERIFIED; ERA5 backfill supplies actuals. COVID: 2020 CANCELLED / virtual; 2021 held virtually (no standard May in-person) — flag both. The 3rd-Sunday-May rule describes every normal year; 2020/2021 May slots remain climatological slots per slot semantics. 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 the race confirms its schedule and race week arrives.
Median start temp
56°F
p75 (a warm year): 59°F
Median dew point
48°F
at the start hour
Rain at the start
15%
3 of 20 measured years
Warmest start
66°F
in 2009
Scroll sideways to see all columns.
| Year | Start temp | Dew point | Wind | Precip (start hr) | Day's high |
|---|---|---|---|---|---|
| 2026 | 55°F | 44°F | 4 mph | dry | 76°F |
| 2025 | 56°F | 47°F | 4 mph | dry | 74°F |
| 2024 | 55°F | 48°F | 8 mph | dry | 69°F |
| 2023 | 55°F | 51°F | 4 mph | dry | 71°F |
| 2022 | 57°F | 53°F | 8 mph | dry | 69°F |
| 2021 | 54°F | 48°F | 8 mph | dry | 63°F |
| 2020 | 62°F | 57°F | 7 mph | 0.2 mm | 72°F |
| 2019 | 53°F | 46°F | 7 mph | 1.3 mm | 59°F |
| 2018 | 55°F | 46°F | 13 mph | dry | 64°F |
| 2017 | 60°F | 51°F | 3 mph | dry | 81°F |
| 2016 | 59°F | 51°F | 5 mph | dry | 72°F |
| 2015 | 55°F | 51°F | 8 mph | dry | 63°F |
| 2014 | 61°F | 51°F | 11 mph | dry | 71°F |
| 2013 | 59°F | 47°F | 3 mph | dry | 78°F |
| 2012 | 59°F | 44°F | 3 mph | dry | 76°F |
| 2011 | 52°F | 44°F | 9 mph | 0.2 mm | 57°F |
| 2010 | 53°F | 47°F | 7 mph | dry | 60°F |
| 2009 | 66°F | 54°F | 1 mph | dry | 88°F |
| 2008 | 56°F | 47°F | 7 mph | dry | 69°F |
| 2007 | 57°F | 42°F | 9 mph | dry | 71°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 12k
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
- Howard St at Main St, SoMa near the Embarcadero (the "Bay" side); point-to-point west through the city to Ocean Beach / the Great Highway (the "Breakers"). Coordinate is the Main & Howard intersection (Nominatim) — near-exact.
- Traditional start (not confirmed for 2027)
- 8:00 AM (America/Los_Angeles) — First (seeded/elite) wave 8:00 AM, subsequent waves through ~8:45 AM (2026 SFMTA + official). Headline gun = 8:00 AM. Many participants start untimed behind the seeded corrals; a scraped "8:45" is the last wave, not the start.
- Field size
- REGISTERED PARTICIPANTS, 2024 edition (May 19, 2024): 20,978 (race director Kyle Meyers, via 2024 press). 2025 preview/coverage put registration "~20,000+"; Wikipedia cites ~25,000 total attendance 2025 (includes untimed). CRITICAL: the famous "50,000–110,000" Bay to Breakers figures are heyday on-course crowd counts (costumes, centipedes, bandits) — NOT registered field or finishers. Timed finishers are fewer than registrants and not separately published in sources checked. Re-verify live before ship (checked 2026-08-27).
- Registration
- open (mass-participation; costume/centipede culture; large untimed contingent)
Wyndo is not affiliated with or endorsed by the Bay to Breakers (officially the "Bay to Breakers") 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.