Coastal Waters Forecast
Issued by NWS Tiyan, Guam

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882
FZMY50 PGUM 181855
CWFGUM

Coastal Waters Forecast for the Mariana Islands
National Weather Service Tiyan GU
455 AM ChST Sun Oct 19 2025

Marianas Waters out to 40 nautical miles

PMZ150-190845-
455 AM ChST Sun Oct 19 2025

.Synopsis for Marianas Waters...
Moderate to fresh trade winds are expected today, tapering down
tonight as the pressure gradient between the tropics and mid-
latitudes decreases. Combined seas of 6 to 8 feet will stay
elevated and choppy through the first half of this week, as
northerly swells and trade swell continue to interact and mix in.
Seas are then expected to decrease once these swells weaken,
especially the northerly swell, which is expected to dissipate by
the second half of this week.

$$

PMZ151>154-190845-
MARIANAS COASTAL WATERS-
455 AM ChST Sun Oct 19 2025

.TODAY...East wind 15 to 20 kt. Seas 5 to 7 ft. Wave Detail: East
5 ft at 9 seconds, east 4 ft at 6 seconds and north 3 ft at
10 seconds. Scattered showers.
.TONIGHT...East wind 10 to 20 kt. Seas 5 to 7 ft. Wave Detail:
East 5 ft at 9 seconds, east 3 ft at 5 seconds and north 2 ft at
10 seconds. Scattered showers.
.MONDAY...East wind 5 to 15 kt. Seas 5 to 7 ft. Wave Detail: East
5 ft at 9 seconds, east 3 ft at 4 seconds and north 3 ft at
13 seconds. Scattered showers.
.MONDAY NIGHT...East wind 5 to 15 kt. Seas 5 to 7 ft. Wave
Detail: East 4 ft at 9 seconds, north 4 ft at 13 seconds and east
3 ft at 4 seconds.
.TUESDAY...Southeast wind 10 to 15 kt. Seas 4 to 6 ft. Wave
Detail: North 4 ft at 13 seconds, east 3 ft at 9 seconds and
southeast 2 ft at 4 seconds. A chance of showers.
.WEDNESDAY...Southeast wind 10 kt. Seas 3 to 5 ft. Wave Detail:
East 3 ft at 9 seconds, north 3 ft at 12 seconds and southeast 2
ft at 4 seconds. A chance of showers.
.THURSDAY...East wind 10 kt. Seas 3 to 5 ft. Wave Detail: East
4 ft at 9 seconds and east 2 ft at 4 seconds. A chance of showers
with a slight chance of thunderstorms.

$$