San Francisco, United States · America/Los_Angeles

Ocean Beach

Cold, steep, and completely exposed. The wind factor dominates everything else on a typical afternoon.

20:00 local · 2026-10-04

36% — the read for this hour

Marginal36%

Swell

0.62 m

Period

8 s

Swell from

219°

Wind

5.1 m/s

Wind from

224°

Air

16°C

Marginal36%

Marginal — one good hour at most. At Ocean Beach on this hour the read is 36%. What earns it: peel speed at 20.0 km/h. What costs it: direction match at 73° off the 292° peel.

12 hours worth driving for today: 00:00, 01:00, 02:00, 03:00, 04:00, 05:00, 06:00, 07:00, 08:00, 10:00, 11:00, 12:00.

Tide window for a beachbreak: 0.8–2.2 m of water over the take-off; below 0.30 m it works across the tide matters and the reef is exposed.

Ocean Beach · 24 hours, local timelive data

score tide (dashed, MLLW) swell height now

Dashed line is the tide above MLLW, solid line is the swell height. Column height is the engine score for that hour. Faded columns are gated. The hour you select is in the URL, so this page is shareable as-is.

Tide station

Station: San Francisco
Datum: MLLW
Range: 1.82 m
Mean: 0.97 m

Signature interaction

Drag the tide and watch the reef change its mind

The cross-section is drawn from the break's own reef slope. Every change re-runs the shared engine on the server and returns a fresh seal — this control cannot work without the API.

Seabed cross-section · Ocean BeachBeachbreak — sand shifting under the take-off

Drag the tide — what-if only, nothing stored is changed

1.56 m

The dashed arrow is the peel, at c = √(g·depth). More water over the take-off means a faster peel, which is why the same swell behaves differently at low and mid tide.

Re-solved by swellread-engine/2026.10.1

Marginal 36%seal 89d4ca3d1761…

Water over take-off: exposed
Break height: 0.26 m
Peel speed: 20.0 km/h
Wave power: 1.9 kW/m

Marginal — one good hour at most. At Ocean Beach on this hour the read is 36%. What earns it: peel speed at 20.0 km/h. What costs it: direction match at 73° off the 292° peel.

Every factor, re-weighted for this tide

Swell power1.9 kW/m · 1.9%
Peel speed20.0 km/h · 19.7%
Wind quality5.1 m/s straight onshore · 0.0%
Tide window3.16 m over the take-off · 10.7%
Direction match73° off the 292° peel · 0.0%
Period cleanliness7.8 s · 4.0%

Show your working

Every factor, its weight, and the arithmetic behind it

Weights are renormalised over the factors that have real data behind them. A factor with no data is dropped and said so, never quietly scored at zero.

Swell power1.9 kW/m · 1.9%
weight 0.220
Peel speed20.0 km/h · 19.7%
weight 0.200
Wind quality5.1 m/s straight onshore · 0.0%
weight 0.200
Tide window3.16 m over the take-off · 10.7%
weight 0.180
Direction match73° off the 292° peel · 0.0%
weight 0.120
Period cleanliness7.8 s · 4.0%
weight 0.080

engine seal 89d4ca3d17619e210de0bb9224a7beec3ab873614e2a7516bf685ab701b132afea08f579860b5fb1f7eeacd8830323e5

Swell power
P = 1/16 · rho · g · Hs² · Tp = 0.628 · 0.62² · 8 = 1.9 kW/m, against a 22 kW/m "serious day" reference.
Peel speed
c = sqrt(g · depth) = sqrt(9.81 · 3.16 m) = 20.0 km/h over a 3.16 m take-off, with 0.26 m standing up. Full marks 8.5–19 km/h: slower is mush, faster than ~25 km/h is unridable.
Wind quality
Wind is straight onshore at 5.1 m/s. Alignment = 1 − (1 + cos 5°)/2 = 0.00; speed envelope at 5.1 m/s = 1.00. Product 0.00.
Tide window
beachbreak works across the tide. Ideal band 0.8–2.2 m of water over the take-off; below 0.30 m the reef is exposed.
Direction match
Swell from 219°, this break peels cleanly from 292°. 73° of error: inside 12° is full marks, past 75° the swell wraps the headland and does not arrive.
Period cleanliness
Tp = 7.8 s. Energy organises between 6 s and 9.5 s; beyond 14 s the swell stands up steeper than a shallow reef can hold, so the score is eased off by up to 35%.

Provenance

Every number above came from one of these

liveOpen-Meteo Marine APICC BY 4.0, non-commercial attribution requiredfetched 2026-10-04 21:13 UTC168 hourly rows, swell and wind wave.
liveOpen-Meteo Forecast APICC BY 4.0, non-commercial attribution requiredfetched 2026-10-04 21:13 UTC168 hourly rows, wind and air.
liveNOAA CO-OPS tide predictionsU.S. Government public domainfetched 2026-10-04 21:13 UTC144 hourly predictions, MLLW datum, station 9414290 (San Francisco).

Snapshot generated 2026-10-04T21:13:26.433Z. Break orientation, reef slope and take-off depth come from this project's catalogue and are labelled as estimates, not survey data.