885
FZMY50 PGUM 210617
CWFGUM

Coastal Waters Forecast for the Mariana Islands
National Weather Service Tiyan GU
417 PM ChST Thu Aug 21 2025

Marianas Waters out to 40 nautical miles

PMZ150-212200-
417 PM ChST Thu Aug 21 2025

.Synopsis for Marianas Waters...A trade-wind trough is moving
through the Marianas, bringing scattered showers and isolated
thunderstorms through Friday. Locally heavy showers with gusts to
20 kt are possible for Guam and Rota tonight. Combined seas of 3
to 4 feet and light to gentle winds are expected over the next few
days, increasing to 3 to 5 foot seas and gentle to moderate trades
next week.

$$

PMZ151-152-212200-
Guam Coastal Waters-Rota Coastal Waters-
417 PM ChST Thu Aug 21 2025

.TONIGHT...East wind 5 to 10 kt. Gusts to 20 kt near heavier
showers. Seas 3 to 4 ft. Wave Detail: East 3 ft at 8 seconds and
east 2 ft at 4 seconds. Scattered showers with isolated
thunderstorms. Locally heavy showers possible.
.FRIDAY...East wind 5 to 10 kt. Seas 3 to 4 ft. Wave Detail: East
3 ft at 8 seconds and east 2 ft at 4 seconds. Scattered showers
with isolated thunderstorms.
.FRIDAY NIGHT...East wind 5 to 10 kt. Seas around 3 ft. Wave
Detail: East 3 ft at 8 seconds and east 2 ft at 4 seconds.
Isolated thunderstorms.
.SATURDAY...East wind 5 kt. Seas around 3 ft. Wave Detail: East
3 ft at 8 seconds. Scattered showers with isolated thunderstorms.
.SATURDAY NIGHT...East wind 5 to 10 kt. Seas around 3 ft. Wave
Detail: East 2 ft at 4 seconds and east 2 ft at 8 seconds.
Isolated thunderstorms.
.SUNDAY...East wind 10 to 15 kt. Seas around 3 ft. Wave Detail:
East 3 ft at 4 seconds and east 2 ft at 8 seconds. A slight
chance of thunderstorms.
.MONDAY THROUGH TUESDAY...East wind 10 to 15 kt. Seas 3 to 5 ft.
Wave Detail: East 3 ft at 4 seconds and east 3 ft at 8 seconds. A
chance of showers with a slight chance of thunderstorms.

$$

PMZ153-154-212200-
Tinian Coastal Waters-Saipan Coastal Waters-
417 PM ChST Thu Aug 21 2025

.TONIGHT...East wind 10 kt. Seas 3 to 4 ft. Wave Detail: East
3 ft at 8 seconds and east 2 ft at 4 seconds. Scattered showers
with isolated thunderstorms.
.FRIDAY...East wind 5 to 10 kt. Seas 3 to 4 ft. Wave Detail: East
3 ft at 8 seconds and east 2 ft at 4 seconds. Scattered showers
and isolated thunderstorms.
.FRIDAY NIGHT...East wind 5 to 10 kt. Seas around 3 ft. Wave
Detail: East 3 ft at 8 seconds and east 2 ft at 4 seconds.
Isolated thunderstorms.
.SATURDAY...East wind 5 to 10 kt. Seas around 3 ft. Wave Detail:
East 3 ft at 8 seconds. Scattered showers with isolated
thunderstorms.
.SATURDAY NIGHT...East wind 5 to 10 kt. Seas around 3 ft. Wave
Detail: East 2 ft at 4 seconds and east 2 ft at 8 seconds.
Isolated thunderstorms.
.SUNDAY...East wind 10 to 15 kt. Seas around 3 ft. Wave Detail:
East 3 ft at 4 seconds and east 2 ft at 8 seconds. A slight
chance of thunderstorms.
.MONDAY THROUGH TUESDAY...Southeast wind 10 to 15 kt. Seas 3 to
5 ft. Wave Detail: East 4 ft at 8 seconds and east 3 ft at
5 seconds. A chance of showers with a slight chance of
thunderstorms.

$$