Oahu North Shore · Wednesday, Sep 23

Backdoor

Oahu north-facing shore forecast; official shore-facing range: 3–5 ft

Updated Tue, Sep 22, 2:20 PM HST

When to go

11:00 AM–1:00 PM

Strong wind — difficult conditions · Low confidence

3–5 ft · Official surf · whole shore and forecast period · Oahu north-facing shore forecast; official shore-facing range

Strong wind: 14.2 kt · cross-shore

Cautions

Strong wind or gusts up to 32.9 kt can make the session difficult; being first in the list does not make conditions good.
Strong wind or gusts up to 33.0 kt can make the session difficult; being first in the list does not make conditions good.

Forecast details

The official forecast calls for surf along this coast.
This is the best time in the forecast, though wind may make it choppy.

Other wind windows

Plan around the wind

The best available upcoming daylight wind sample to compare with the wave evidence. This compares wind only; wave size, tide suitability, and hazards can change your choice.

11:00 AM–1:00 PM · Pacific/Honolulu
Strong wind · up to 14.2 kt · reported gusts up to 33.0 kt
Caution: This is the best available wind comparison, not a favorable-wind label. Strong wind remains in the selected evidence.
Offshore waves: 6.7–6.8 ft across the period. Surf height unavailable. Tide data available; check the local tide response.
Wind source time: Sep 22, 1:45 PM HST. This is not the model run issue time.

How these periods are chosen

The planner prefers three consecutive hourly samples covering two daylight hours, but retains shorter one- or two-sample evidence when that is all the forecast provides. Light wind means at most 6 kt. Moderate offshore means at most 12 kt from land toward the sea when shore orientation is verified. Strong wind or known gusts of 20 kt or more remain visible as cautions instead of making the entire comparison disappear. These are comparison labels, not locally tested surf-quality or safety ratings. Missing gusts remain unknown. Terrain shelter, currents, closures, and your ability are not assessed.

Forecast confidence

Returned marine grid point is 13.8 km from the mapped spot. MFWAM is approximately 8 km resolution.
Reference model hour: 18 hours from now; historical residuals do not measure forecast lead-time error.
Historical test error 1.1 ft across 169 observations; 81% interval coverage.
This direction/period regime: 55 test observations, signed bias 0.9 ft, 85% observed interval coverage. The 80% calibration target is not a probability guarantee for this forecast.
Forecast lead-time error, ensemble spread, local tide response, and human quality labels have not been validated.
A mapped coordinate does not establish nearshore grid resolution or terrain/shelter accuracy.

Wind ENE 14.5 kt

Tide 0.5 ft rising

Wave, wind and tide details

Surf height1–4 ftEstimated · Low confidence

Estimate details

80% historical prediction intervalTypical estimate 2.4 ft · not upper sets

Offshore model swellE 4.9 ft @ 8sValid 2026-09-23 08:00 · Pacific/HonoluluMarine grid 21.7917, -158.0417 · offshore model, not a local measurement

Offshore model sea6.7 ft @ 7.9sSignificant wave height including wind waves and swell; not breaking surfValid 2026-09-23 08:00 · Pacific/Honolulu

Model windENE 14.5 ktcross-shoreValid 2026-09-23 08:00 · Pacific/Honolulu7.3 kt offshore component

Tide0.5 ftrisingNOAA HALEIWA, WAIALUA BAY, OAHU IS 1612668 · 9.7 km from Backdoor · predicted height relative to MLLWRetrieved Sep 22, 2:28 PM HST · provider issue time unavailable33% of adjacent local low–high range · descriptive, not a safety rating

Surf and wind

Recommended window: No recommended window

Historical midpoint interval Recommended window Top hourWind arrows point from the reported direction

Hourly forecast

Hourly surf forecast for Backdoor
Time	Surf height	Wind	Tide	Offshore swell
12 AM	0.5–3.5 ft	E 13.7 ktcross-shore	1 ftrising	ENE 4.5 ft @ 7s
1 AM	0.5–3.5 ft	E 13.8 ktcross-shore	1 ftnear high	E 4.6 ft @ 7s
2 AM	0.5–3.5 ft	E 13.9 ktcross-shore	1 ftfalling	E 4.7 ft @ 7s
3 AM	0.5–4 ft	ENE 14 ktcross-shore	0.5 ftfalling	E 4.7 ft @ 7s
4 AM	0.5–4 ft	E 13.7 ktcross-shore	0.5 ftfalling	E 4.7 ft @ 7s
5 AM	1–4 ft	E 13.7 ktcross-shore	0.5 ftnear low	E 4.7 ft @ 8s
6 AM	1–4 ft	E 14.5 ktcross-shore	0.5 ftrising	E 4.8 ft @ 8s
7 AM	1–4 ft	E 14.4 ktcross-shore	0.5 ftrising	E 4.8 ft @ 8s
8 AM	1–4 ft	ENE 14.5 ktcross-shore	0.5 ftrising	E 4.9 ft @ 8s
9 AM	1–4 ft	ENE 14.4 ktcross-shore	1 ftrising	E 4.7 ft @ 8s
10 AM	1–4 ft	ENE 14.6 ktcross-shore	1 ftrising	E 4.5 ft @ 8s
11 AM	1–4 ft	ENE 13.9 ktcross-shore	1 ftrising	E 4.3 ft @ 8s
Noon	1–4 ft	E 14.2 ktcross-shore	1.5 ftrising	E 4.4 ft @ 8s
1 PM	1–4 ft	E 14.1 ktcross-shore	1.5 ftnear high	E 4.5 ft @ 8s
2 PM	1–4 ft	ENE 14.6 ktcross-shore	1.5 ftfalling	E 4.6 ft @ 8s
3 PM	1–4 ft	ENE 14.7 ktcross-shore	1 ftfalling	E 4.5 ft @ 8s
4 PM	0.5–4 ft	ENE 14.8 ktcross-shore	1 ftfalling	E 4.5 ft @ 8s
5 PM	0.5–4 ft	ENE 14.2 ktcross-shore	0.5 ftfalling	E 4.4 ft @ 7s
6 PM	0.5–4 ft	ENE 14.1 ktcross-shore	0.5 ftfalling	E 4.2 ft @ 7s
7 PM	0.5–3.5 ft	ENE 14.4 ktcross-shore	0 ftrising	E 4.0 ft @ 7s
8 PM	0.5–3.5 ft	ENE 14.5 ktcross-shore	0.5 ftrising	E 3.8 ft @ 7s
9 PM	0.5–3.5 ft	ENE 14.8 ktcross-shore	0.5 ftrising	E 3.7 ft @ 7s
10 PM	0.5–3.5 ft	ENE 14.4 ktcross-shore	0.5 ftrising	E 3.6 ft @ 7s
11 PM	0.5–3.5 ft	ENE 14.5 ktcross-shore	0.5 ftrising	E 3.5 ft @ 8s

12 AM0.5–3.5 ft

WindE 13.7 ktcross-shoreTide1 ftrisingOffshore swellENE 4.5 ft @ 7s

1 AM0.5–3.5 ft

WindE 13.8 ktcross-shoreTide1 ftnear highOffshore swellE 4.6 ft @ 7s

2 AM0.5–3.5 ft

WindE 13.9 ktcross-shoreTide1 ftfallingOffshore swellE 4.7 ft @ 7s

3 AM0.5–4 ft

WindENE 14 ktcross-shoreTide0.5 ftfallingOffshore swellE 4.7 ft @ 7s

4 AM0.5–4 ft

WindE 13.7 ktcross-shoreTide0.5 ftfallingOffshore swellE 4.7 ft @ 7s

5 AM1–4 ft

WindE 13.7 ktcross-shoreTide0.5 ftnear lowOffshore swellE 4.7 ft @ 8s

6 AM1–4 ft

WindE 14.5 ktcross-shoreTide0.5 ftrisingOffshore swellE 4.8 ft @ 8s

7 AM1–4 ft

WindE 14.4 ktcross-shoreTide0.5 ftrisingOffshore swellE 4.8 ft @ 8s

8 AM1–4 ft

WindENE 14.5 ktcross-shoreTide0.5 ftrisingOffshore swellE 4.9 ft @ 8s

9 AM1–4 ft

WindENE 14.4 ktcross-shoreTide1 ftrisingOffshore swellE 4.7 ft @ 8s

10 AM1–4 ft

WindENE 14.6 ktcross-shoreTide1 ftrisingOffshore swellE 4.5 ft @ 8s

11 AM1–4 ft

WindENE 13.9 ktcross-shoreTide1 ftrisingOffshore swellE 4.3 ft @ 8s

Noon1–4 ft

WindE 14.2 ktcross-shoreTide1.5 ftrisingOffshore swellE 4.4 ft @ 8s

1 PM1–4 ft

WindE 14.1 ktcross-shoreTide1.5 ftnear highOffshore swellE 4.5 ft @ 8s

2 PM1–4 ft

WindENE 14.6 ktcross-shoreTide1.5 ftfallingOffshore swellE 4.6 ft @ 8s

3 PM1–4 ft

WindENE 14.7 ktcross-shoreTide1 ftfallingOffshore swellE 4.5 ft @ 8s

4 PM0.5–4 ft

WindENE 14.8 ktcross-shoreTide1 ftfallingOffshore swellE 4.5 ft @ 8s

5 PM0.5–4 ft

WindENE 14.2 ktcross-shoreTide0.5 ftfallingOffshore swellE 4.4 ft @ 7s

6 PM0.5–4 ft

WindENE 14.1 ktcross-shoreTide0.5 ftfallingOffshore swellE 4.2 ft @ 7s

7 PM0.5–3.5 ft

WindENE 14.4 ktcross-shoreTide0 ftrisingOffshore swellE 4.0 ft @ 7s

8 PM0.5–3.5 ft

WindENE 14.5 ktcross-shoreTide0.5 ftrisingOffshore swellE 3.8 ft @ 7s

9 PM0.5–3.5 ft

WindENE 14.8 ktcross-shoreTide0.5 ftrisingOffshore swellE 3.7 ft @ 7s

10 PM0.5–3.5 ft

WindENE 14.4 ktcross-shoreTide0.5 ftrisingOffshore swellE 3.6 ft @ 7s

11 PM0.5–3.5 ft

WindENE 14.5 ktcross-shoreTide0.5 ftrisingOffshore swellE 3.5 ft @ 8s

Tide

NOAA HALEIWA, WAIALUA BAY, OAHU IS 1612668 · 9.7 km from Backdoor · MLLW

Interpolated tide height Recommended window

About this spot

Model-grid forecast requested at the mapped coordinate; reef, headland, and nearshore transformations are unresolved. Reef break. Named break currentLocation coordinate adjacent to Pipeline; published map precision is not a coastline survey. Orientation retained from the reviewed catalog geometry.

Mapped spot coordinate: 21.668, -158.052.

Oahu · north · Ocean-facing bearing 315° · Location provenance

Model request point: Backdoor (21.668, -158.052). Model output times describe valid conditions; the provider does not expose the model run issue time in this response.

Forecast sources

Data coverage 4/6 sources

Source availability is not forecast accuracy. Where an empirical model passes historical testing, its error and interval coverage are shown above. Source count cannot increase that confidence.

Coverage tier A+ · US_HAWAII · spot-level model point

Oahu north-facing shore forecast; official shore-facing range3–5 ftCurrent · Sep 22, 8:56 AM HST

US National Weather Service Surf Zone Forecast
Oahu north-facing shore forecast; official breaking-surf rangeCurrentSep 22, 8:56 AM HST
NWS Honolulu Surf Observations
Current human surf observations are not forecasts for the selected future date.Not applicableSep 21, 11:05 AM HST
PacIOOS ERDDAP
Wave buoy observations and regional ocean datasets; market adapter or station mapping not connectedUnavailableNo source time
Waimea Bay buoy 51201 (regional north-shore observation)
Current buoy observations are not forecasts for the selected future date.Not applicableSep 22, 1:56 PM HST
Coastal Data Information Program THREDDS
No exact named CDIP mapping is available.UnavailableNo source time
Haleiwa, Waialua Bay station 1612668 (MLLW)
NOAA HALEIWA, WAIALUA BAY, OAHU IS 1612668 · 9.7 km from Backdoor; predicted high/low events above MLLW, converted to feet. Timestamp is retrieval time; provider issue time is not supplied.CurrentSep 22, 2:28 PM HST
Open-Meteo Marine API
1 of 1 configured model points availableCurrentSep 22, 1:45 PM HST
Open-Meteo Weather API
1 of 1 configured model points availableCurrentSep 22, 1:45 PM HST
Surf-Forecast public pages
Spot discovery and break-specific HTML fallbackNot applicableNo source time
Surfline public spot pages
Break-specific comparison, cams, and metadataNot applicableNo source time

How best guesses are made

Best guesses combine usable wave and wind evidence, with qualitative confidence and specific limitations. A missing tide or local surf-height model does not prevent useful guidance. Tide levels use the named station datum; their effect at this break remains uncertain. Wind direction is relative to the mapped beach orientation, without calibrated terrain or shelter effects. The comparison is a heuristic, not a measured quality rating.