San Francisco, United States · America/Los_Angeles

Ocean Beach

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

21:00 local · 2026-10-04

44% — the read for this hour

Marginal44%

Swell

0.60 m

Period

9 s

Swell from

212°

Wind

4.6 m/s

Wind from

228°

Air

15°C

Marginal44%

Marginal — one good hour at most. At Ocean Beach on this hour the read is 44%. What earns it: peel speed at 19.1 km/h. What costs it: direction match at 80° 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

1.26 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 44%seal 0b43a42be973…

Water over take-off: exposed
Break height: 0.25 m
Peel speed: 19.1 km/h
Wave power: 2.0 kW/m

Marginal — one good hour at most. At Ocean Beach on this hour the read is 44%. What earns it: peel speed at 19.1 km/h. What costs it: direction match at 80° off the 292° peel.

Every factor, re-weighted for this tide

Swell power2.0 kW/m · 2.0%
Peel speed19.1 km/h · 20.0%
Wind quality4.6 m/s straight onshore · 0.4%
Tide window2.86 m over the take-off · 14.1%
Direction match80° off the 292° peel · 0.0%
Period cleanliness9.0 s · 7.6%

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 power2.0 kW/m · 2.0%
weight 0.220
Peel speed19.1 km/h · 20.0%
weight 0.200
Wind quality4.6 m/s straight onshore · 0.4%
weight 0.200
Tide window2.86 m over the take-off · 14.1%
weight 0.180
Direction match80° off the 292° peel · 0.0%
weight 0.120
Period cleanliness9.0 s · 7.6%
weight 0.080

engine seal 0b43a42be973a0c5723e32361c08fe3c9049a04c4eb738c68da73dce24647887c97585b45f56ba8ccb23ee4f4e25d7e0

Swell power
P = 1/16 · rho · g · Hs² · Tp = 0.628 · 0.60² · 9 = 2.0 kW/m, against a 22 kW/m "serious day" reference.
Peel speed
c = sqrt(g · depth) = sqrt(9.81 · 2.86 m) = 19.1 km/h over a 2.86 m take-off, with 0.25 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 4.6 m/s. Alignment = 1 − (1 + cos 16°)/2 = 0.02; speed envelope at 4.6 m/s = 1.00. Product 0.02.
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 212°, this break peels cleanly from 292°. 80° of error: inside 12° is full marks, past 75° the swell wraps the headland and does not arrive.
Period cleanliness
Tp = 9.0 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 20:30 UTC168 hourly rows, swell and wind wave.
liveOpen-Meteo Forecast APICC BY 4.0, non-commercial attribution requiredfetched 2026-10-04 20:30 UTC168 hourly rows, wind and air.
liveNOAA CO-OPS tide predictionsU.S. Government public domainfetched 2026-10-04 20:30 UTC144 hourly predictions, MLLW datum, station 9414290 (San Francisco).

Snapshot generated 2026-10-04T20:30:35.601Z. Break orientation, reef slope and take-off depth come from this project's catalogue and are labelled as estimates, not survey data.