979
FZMY50 PGUM 181855
CWFGUM

Coastal Waters Forecast for the Mariana Islands
National Weather Service Tiyan GU
455 AM ChST Sat Sep 19 2026

Marianas Waters out to 40 nautical miles

PMZ150-191030-
455 AM ChST Sat Sep 19 2026

.Synopsis for Marianas Waters...
Gentle to moderate west to southwest winds will decrease to light
to gentle starting today, then shift to the south to southeast
next week. Combined seas of 5 to 7 feet are comprised of southwest
monsoon swell, northerly swell from distant Typhoon Dujuan, and
light northeast swell. Seas are expected to subside to 4 to 6 feet
over the weekend and into early next week due to a slight
decrease in wind waves and swells. Trailing monsoon showers linger
nearby, but mainly south of Guam. Scattered showers and isolated
thunderstorms prevail across the region, moreso across Guam and
Rota through today, then showers spread northward across Tinian
and Saipan early next week. A couple periods of numerous showers
are expected late Sunday night across the region.

$$

PMZ151-152-191030-
Guam Coastal Waters-Rota Coastal Waters-
455 AM ChST Sat Sep 19 2026

.TODAY...Southwest wind 5 to 15 kt. Seas 5 to 6 ft. Wave Detail:
Southwest 4 ft at 8 seconds, north 3 ft at 8 seconds, southwest 3
ft at 4 seconds and northeast 2 ft at 10 seconds. Scattered
showers with isolated thunderstorms.
.TONIGHT...West wind 5 to 10 kt. Seas 4 to 6 ft. Wave Detail:
Southwest 4 ft at 8 seconds, north 3 ft at 8 seconds, northeast 2
ft at 10 seconds, and west 2 ft at 4 seconds. Scattered showers
with isolated thunderstorms.
.SUNDAY...West wind 10 kt. Seas 4 to 6 ft. Wave Detail: North 3
ft at 8 seconds, southwest 3 ft at 8 seconds and northeast 3 ft
at 10 seconds. Scattered showers with isolated thunderstorms.
.SUNDAY NIGHT...Variable wind 5 kt. Seas around 5 ft. Wave
Detail: North 3 ft at 8 seconds, southwest 3 ft at 8 seconds and
northeast 3 ft at 10 seconds. Isolated thunderstorms. Scattered
showers in the evening, then numerous showers after midnight.
.MONDAY THROUGH WEDNESDAY...South wind 5 to 10 kt. Seas 4 to
5 ft. Wave Detail: North 4 ft at 12 seconds, southwest 3 ft at
8 seconds, northeast 3 ft at 10 seconds and southeast 2 ft at
4 seconds. A chance of showers with a slight chance of
thunderstorms.

$$

PMZ153-154-191030-
Tinian Coastal Waters-Saipan Coastal Waters-
455 AM ChST Sat Sep 19 2026

.TODAY...Southwest wind 5 to 10 kt. Seas 5 to 6 ft. Wave Detail:
Southwest 4 ft at 8 seconds, north 3 ft at 8 seconds, southwest 2
ft at 4 seconds and northeast 2 ft at 10 seconds. Scattered
showers with isolated thunderstorms.
.TONIGHT...West wind 5 kt. Seas 4 to 6 ft. Wave Detail:
Southwest 4 ft at 8 seconds, north 3 ft at 8 seconds and
northeast 3 ft at 10 seconds. Scattered showers with isolated
thunderstorms.
.SUNDAY...Variable wind 5 kt. Seas 4 to 6 ft. Wave Detail:
Southwest 4 ft at 9 seconds, north 3 ft at 10 seconds and
northeast 3 ft at 10 seconds. Scattered showers with isolated
thunderstorms.
.SUNDAY NIGHT...Variable wind 5 kt. Seas around 5 ft. Wave
Detail: North 3 ft at 9 seconds, northeast 3 ft at 10 seconds and
southwest 3 ft at 10 seconds. Isolated thunderstorms. Scattered
showers in the evening, then numerous showers after midnight.
.MONDAY THROUGH WEDNESDAY...Southeast wind 10 kt. Seas 4 to 6 ft.
Wave Detail: Northeast 4 ft at 10 seconds, north 3 ft at
11 seconds, southeast 2 ft at 4 seconds and southwest 2 ft at
8 seconds. A chance of showers with a slight chance of
thunderstorms.

$$