


Coastal Waters Forecast
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
345 FZMY50 PGUM 171853 CWFGUM Coastal Waters Forecast for the Mariana Islands National Weather Service Tiyan GU 453 AM ChST Sat Oct 18 2025 Marianas Waters out to 40 nautical miles PMZ150-180900- 453 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. $$ PMZ151>154-180900- MARIANAS COASTAL WATERS- 453 AM ChST Sat Oct 18 2025 .TODAY...East wind 15 kt with gusts to 25 kt. Seas 5 to 7 ft. Wave Detail: East 5 ft at 9 seconds, east 3 ft at 5 seconds and north 3 ft at 12 seconds. Scattered showers. .TONIGHT...East wind 15 to 20 kt. Seas 6 to 8 ft. Wave Detail: East 5 ft at 9 seconds, east 4 ft at 6 seconds and north 3 ft at 11 seconds. .SUNDAY...East wind 15 to 20 kt. Seas 5 to 7 ft. Wave Detail: East 6 ft at 8 seconds, east 3 ft at 5 seconds and north 3 ft at 10 seconds. .SUNDAY NIGHT...East wind 10 to 15 kt. Seas 5 to 7 ft. Wave Detail: East 5 ft at 8 seconds, east 3 ft at 5 seconds and north 2 ft at 10 seconds. Scattered showers. .MONDAY...East wind 10 to 15 kt. Seas 5 to 7 ft. Wave Detail: East 5 ft at 8 seconds, north 4 ft at 13 seconds and east 2 ft at 4 seconds. A chance of showers. .TUESDAY...Southeast wind 10 to 15 kt. Seas 6 to 8 ft. Wave Detail: East 5 ft at 9 seconds, north 4 ft at 13 seconds and southeast 2 ft at 4 seconds. A chance of showers. .WEDNESDAY...Southeast wind 10 kt. Seas 5 to 7 ft. Wave Detail: East 5 ft at 9 seconds, north 3 ft at 12 seconds and southeast 2 ft at 4 seconds. A chance of showers. $$