


Coastal Waters Forecast
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
818 FZMY50 PGUM 180108 CCA CWFGUM Coastal Waters Forecast for the Mariana Islands...CORRECTED National Weather Service Tiyan GU 1108 AM ChST Sat Oct 18 2025 Marianas Waters out to 40 nautical miles PMZ150-180900- 1108 AM ChST Sat Oct 18 2025 .Synopsis for Marianas Waters... Moderate to fresh trade winds are expected through Sunday, tapering down thereafter as the pressure gradient between the tropics and mid-latitudes decreases. Combined seas of 6 to 8 feet will stay elevated and choppy through at least the weekend, as northerly swells and trade swell continue to mix in, before tapering down by the middle of next week. $$ PMZ151>154-180900- MARIANAS COASTAL WATERS- 1108 AM ChST Sat Oct 18 2025 Corrected typo in today`s forecast. .TODAY...East wind 15 to 20 kt with occasional gusts to 25 kt. Seas 5 to 7 ft. Wave Detail: East 5 ft at 9 seconds, east 3 ft at 5 seconds and north 3 ft at 12 seconds. Scattered showers and isolated thunderstorms. .TONIGHT...East wind 15 to 20 kt. Seas 6 to 8 ft. Wave Detail: East 5 ft at 9 seconds, east 4 ft at 6 seconds and north 3 ft at 11 seconds. .SUNDAY...East wind 15 to 20 kt. Seas 5 to 7 ft. Wave Detail: East 6 ft at 8 seconds, east 3 ft at 5 seconds and north 3 ft at 10 seconds. .SUNDAY NIGHT...East wind 10 to 15 kt. Seas 5 to 7 ft. Wave Detail: East 5 ft at 8 seconds, east 3 ft at 5 seconds and north 2 ft at 10 seconds. Scattered showers. .MONDAY...East wind 10 to 15 kt. Seas 5 to 7 ft. Wave Detail: East 5 ft at 8 seconds, north 4 ft at 13 seconds and east 2 ft at 4 seconds. A chance of showers. .TUESDAY...Southeast wind 10 to 15 kt. Seas 6 to 8 ft. Wave Detail: East 5 ft at 9 seconds, north 4 ft at 13 seconds and southeast 2 ft at 4 seconds. A chance of showers. .WEDNESDAY...Southeast wind 10 kt. Seas 5 to 7 ft. Wave Detail: East 5 ft at 9 seconds, north 3 ft at 12 seconds and southeast 2 ft at 4 seconds. A chance of showers. $$