Guam · Today

Umatac

NWS Guam · west-facing reefs; official reef-face range: 2–4 ft

Updated Wed, Sep 23, 9:30 AM GMT+10

When to go

Around 6:00 PM

Windy · Low confidence

5.0–5.0 ft · Offshore waves · not face height

Wind: 6.2 kt · cross-shore

Forecast details

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.

4:00 PM–6:00 PM · Pacific/Guam
Unfavorable wind · up to 8.8 kt · reported gusts up to 19.8 kt
Caution: This is the best available wind comparison, not a favorable-wind label. The selected wind is unfavorable for this break.
Offshore waves: 5.0–5.1 ft across the period. Surf height unavailable. Tide data available; check the local tide response.
Wind source time: Sep 23, 9:30 AM GMT+10. 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 2.5 km from the mapped spot. Provider grid resolution is not established for this response.
Reference model hour: 0 hours from now; historical residuals do not measure forecast lead-time error.
No accepted local model for these inputs: missing history, unsupported direction/period/height, or failed historical validation.
A mapped coordinate does not establish nearshore grid resolution or terrain/shelter accuracy.

Wind SSW 10.5 kt

Tide 0.5 ft falling

Wave, wind and tide details

Offshore model swellWSW 3.3 ft @ 6sValid 2026-09-23 10:00 · Pacific/GuamMarine grid 13.2917, 144.6250 · offshore model, not a local measurement

Offshore model sea5.2 ft @ 7.5sSignificant wave height including wind waves and swell; not breaking surfValid 2026-09-23 10:00 · Pacific/Guam

Model windSSW 10.5 ktcross-shoreValid 2026-09-23 10:00 · Pacific/Guam4.1 kt onshore component

Tide0.5 ftfallingNOAA Apra Harbor, Guam 1630000 · 17 km from spot · predicted height relative to MLLWRetrieved Sep 23, 9:35 AM GMT+10 · provider issue time unavailable19% of adjacent local low–high range · descriptive, not a safety rating

NWS Guam · west-facing reefs

Rip Current Risk.....Moderate *. Surf Height North facing reefs............5 to 7 feet. East facing reefs............3 to 5 feet. South facing reefs............2 to 4 feet. West facing reefs............2 to 4 feet. Swell/Period Primary swell................North at 4 to 5 feet. Primary period...............9 seconds. Secondary swell..............Northeast at around 2 feet. Secondary period.............10 seconds. Water Temperature Pago buoy..........85 Degrees. Max Heat Index.........Around 100. Winds...............South at 10 to 15 mph.

TODAYOfficial breaking-surf height for the named Guam reef face; conditions vary within that island-facing zoneIssued Sep 23, 3:12 AM GMT+10

NWS Guam · west-facing reefs

Rip Current Risk.....Moderate *. Surf Height North facing reefs............4 to 6 feet. East facing reefs............3 to 5 feet. South facing reefs............2 to 4 feet. West facing reefs............2 to 4 feet. Swell/Period Primary swell................North at 3 to 4 feet. Primary period...............8 seconds. Secondary swell..............Northeast at around 2 feet. Secondary period.............9 seconds. Winds...............Southwest at 10 to 15 mph.

TONIGHTOfficial breaking-surf height for the named Guam reef face; conditions vary within that island-facing zoneIssued Sep 23, 3:12 AM GMT+10

Surf height unavailable. Coastal and offshore waves are not breaking-wave heights.

Surf and wind

Recommended window: No recommended window

Breaking surf is not reliably resolved. Hourly offshore swell and wind inputs are listed below.

Hourly forecast

Hourly surf forecast for Umatac
Time	Wind	Tide	Offshore swell
12 AM	SSE 9.1 ktcross-shore	1.5 ftrising	WSW 3.1 ft @ 6s
1 AM	SSE 8.7 ktcross-shore	1.5 ftrising	WNW 3.2 ft @ 6s
2 AM	SSE 7.2 ktcross-shore	1.5 ftrising	WSW 3.3 ft @ 6s
3 AM	SSE 8.9 ktcross-shore	2 ftrising	SW 3.3 ft @ 6s
4 AM	S 7.8 ktcross-shore	2 ftnear high	SSW 3.4 ft @ 5s
5 AM	S 8 ktcross-shore	2 ftfalling	SSW 3.5 ft @ 5s
6 AM	S 9.1 ktcross-shore	1.5 ftfalling	SSW 3.5 ft @ 5s
7 AM	SSW 9.4 ktcross-shore	1.5 ftfalling	SSW 3.5 ft @ 5s
8 AM	SSW 10.5 ktcross-shore	1 ftfalling	SW 3.5 ft @ 5s
9 AM	SSW 9.1 ktcross-shore	1 ftfalling	WSW 3.3 ft @ 5s
10 AM	SSW 10.5 ktcross-shore	0.5 ftfalling	WSW 3.3 ft @ 6s
11 AM	SSW 12.2 ktcross-shore	0.5 ftnear low	WSW 3.4 ft @ 6s
Noon	SSW 11.7 ktcross-shore	0.5 ftrising	SW 3.5 ft @ 5s
1 PM	SSW 11.1 ktcross-shore	0.5 ftrising	SSW 3.7 ft @ 5s
2 PM	SSW 11 ktcross-shore	1 ftrising	SSW 3.7 ft @ 5s
3 PM	SSW 9.7 ktcross-shore	1.5 ftrising	SSW 3.7 ft @ 5s
4 PM	SW 8.8 ktcross-shore	1.5 ftrising	SW 3.7 ft @ 5s
5 PM	SW 8.1 ktcross-shore	2 ftrising	SW 3.7 ft @ 5s
6 PM	SSW 6.2 ktcross-shore	2 ftnear high	SW 3.7 ft @ 5s
7 PM	SW 5.2 ktcross-shore	2 ftfalling	SW 3.7 ft @ 5s
8 PM	SW 4.6 ktonshore	2 ftfalling	SW 3.7 ft @ 5s
9 PM	WSW 5 ktonshore	2 ftfalling	SW 3.5 ft @ 5s
10 PM	WSW 5.4 ktonshore	1.5 ftfalling	SW 3.5 ft @ 5s
11 PM	W 6.1 ktonshore	1.5 ftfalling	SW 3.4 ft @ 5s

12 AMUnavailable

WindSSE 9.1 ktcross-shoreTide1.5 ftrisingOffshore swellWSW 3.1 ft @ 6s

1 AMUnavailable

WindSSE 8.7 ktcross-shoreTide1.5 ftrisingOffshore swellWNW 3.2 ft @ 6s

2 AMUnavailable

WindSSE 7.2 ktcross-shoreTide1.5 ftrisingOffshore swellWSW 3.3 ft @ 6s

3 AMUnavailable

WindSSE 8.9 ktcross-shoreTide2 ftrisingOffshore swellSW 3.3 ft @ 6s

4 AMUnavailable

WindS 7.8 ktcross-shoreTide2 ftnear highOffshore swellSSW 3.4 ft @ 5s

5 AMUnavailable

WindS 8 ktcross-shoreTide2 ftfallingOffshore swellSSW 3.5 ft @ 5s

6 AMUnavailable

WindS 9.1 ktcross-shoreTide1.5 ftfallingOffshore swellSSW 3.5 ft @ 5s

7 AMUnavailable

WindSSW 9.4 ktcross-shoreTide1.5 ftfallingOffshore swellSSW 3.5 ft @ 5s

8 AMUnavailable

WindSSW 10.5 ktcross-shoreTide1 ftfallingOffshore swellSW 3.5 ft @ 5s

9 AMUnavailable

WindSSW 9.1 ktcross-shoreTide1 ftfallingOffshore swellWSW 3.3 ft @ 5s

10 AMUnavailable

WindSSW 10.5 ktcross-shoreTide0.5 ftfallingOffshore swellWSW 3.3 ft @ 6s

11 AMUnavailable

WindSSW 12.2 ktcross-shoreTide0.5 ftnear lowOffshore swellWSW 3.4 ft @ 6s

NoonUnavailable

WindSSW 11.7 ktcross-shoreTide0.5 ftrisingOffshore swellSW 3.5 ft @ 5s

1 PMUnavailable

WindSSW 11.1 ktcross-shoreTide0.5 ftrisingOffshore swellSSW 3.7 ft @ 5s

2 PMUnavailable

WindSSW 11 ktcross-shoreTide1 ftrisingOffshore swellSSW 3.7 ft @ 5s

3 PMUnavailable

WindSSW 9.7 ktcross-shoreTide1.5 ftrisingOffshore swellSSW 3.7 ft @ 5s

4 PMUnavailable

WindSW 8.8 ktcross-shoreTide1.5 ftrisingOffshore swellSW 3.7 ft @ 5s

5 PMUnavailable

WindSW 8.1 ktcross-shoreTide2 ftrisingOffshore swellSW 3.7 ft @ 5s

6 PMUnavailable

WindSSW 6.2 ktcross-shoreTide2 ftnear highOffshore swellSW 3.7 ft @ 5s

7 PMUnavailable

WindSW 5.2 ktcross-shoreTide2 ftfallingOffshore swellSW 3.7 ft @ 5s

8 PMUnavailable

WindSW 4.6 ktonshoreTide2 ftfallingOffshore swellSW 3.7 ft @ 5s

9 PMUnavailable

WindWSW 5 ktonshoreTide2 ftfallingOffshore swellSW 3.5 ft @ 5s

10 PMUnavailable

WindWSW 5.4 ktonshoreTide1.5 ftfallingOffshore swellSW 3.5 ft @ 5s

11 PMUnavailable

WindW 6.1 ktonshoreTide1.5 ftfallingOffshore swellSW 3.4 ft @ 5s

Tide

NOAA Apra Harbor, Guam 1630000 · 17 km from spot · 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. Mapped reef is outside Umatac Bay on Guam's southwest shore; NWS west-facing reef zone assigned.

Mapped spot coordinate: 13.2945, 144.6482.

Guam · Philippine Sea southwest bay reef · Ocean-facing bearing 270° · Location provenance

Model request point: Umatac (13.2945, 144.6482). Model output times describe valid conditions; the provider does not expose the model run issue time in this response.

Forecast sources

Data coverage 4/9 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_PACIFIC_TERRITORIES · spot-level model point

NWS Guam · west-facing reefs; official reef-face range2–4 ftCurrent · Sep 23, 3:12 AM GMT+10

NWS Guam · west-facing reefs
NWS Guam · west-facing reefs; Official breaking-surf height for the named Guam reef face; conditions vary within that island-facing zoneCurrentSep 23, 3:12 AM GMT+10
US National Weather Service Coastal Waters Forecast
No current identified NWS Marianas Coastal Waters Forecast passed validation.UnavailableNo source time
PacIOOS ERDDAP
Wave buoy observations and regional ocean datasets; market adapter or station mapping not connectedUnavailableNo source time
NOAA NDBC real-time station files
Guam wave buoys 52200 and 52202 no longer publish NDBC real-time files; no wave observation substituted.UnavailableNo source time
Coastal Data Information Program THREDDS
No exact named CDIP mapping is available.UnavailableNo source time
NOAA CO-OPS Tides and Currents API
NOAA Apra Harbor, Guam 1630000 · 17 km from spot; predicted high/low events above MLLW, converted to feet. Timestamp is retrieval time; provider issue time is not supplied.CurrentSep 23, 9:35 AM GMT+10
WorldTides API
Tide predictions and station lookup; market adapter or station mapping not connectedUnavailableNo source time
Open-Meteo Marine API
1 of 1 configured model points availableCurrentSep 23, 9:30 AM GMT+10
Open-Meteo Weather API
1 of 1 configured model points availableCurrentSep 23, 9:30 AM GMT+10
Surf-Forecast public pages
Spot discovery and break-specific HTML fallbackNot 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.