FZMY50 PGUM 210650 CWFGUM Coastal Waters Forecast for the Mariana Islands National Weather Service Tiyan GU 450 PM ChST Sat Mar 21 2026 Marianas Waters out to 40 nautical miles PMZ150-212200- 450 PM ChST Sat Mar 21 2026 .Synopsis for Marianas Waters... Elevated northeast to east swell and wind waves, and long-period north to northeast swell continues to produce hazardous seas up to 10 feet within the eastern Marianas coastal waters, with 7 to 9 feet expected west of the islands. Combined seas may briefly diminish around Sunday night, increasing once more through Monday as the northeast swell and wind waves are reinforced by a building trade-wind surge. Winds will be moderate to fresh out of the northeast to east, briefly becoming moderate to strong Monday and Monday night, then gradually diminishing to light to gentle late week. An extension or another issuance of a Small Craft Advisory will likely be needed for hazardous conditions on Monday and Monday night. $$ PMZ153-154-212200- Tinian Coastal Waters-Saipan Coastal Waters- 450 PM ChST Sat Mar 21 2026 ...SMALL CRAFT ADVISORY IN EFFECT THROUGH SUNDAY AFTERNOON... .TONIGHT...Northeast wind 20 kt. Seas 8 to 10 ft. Wave Detail: Northeast 7 ft at 8 seconds, northeast 5 ft at 6 seconds, north 5 ft at 13 seconds and northeast 3 ft at 14 seconds. .SUNDAY...Northeast wind 20 kt. Seas 8 to 10 ft. Wave Detail: Northeast 8 ft at 8 seconds, northeast 5 ft at 7 seconds, north 3 ft at 12 seconds and northeast 3 ft at 14 seconds. .SUNDAY NIGHT...Northeast wind 15 to 20 kt with occasional gusts to 30 kt. Seas 7 to 9 ft. Wave Detail: Northeast 7 ft at 8 seconds, northeast 5 ft at 7 seconds, northeast 3 ft at 12 seconds and north 2 ft at 11 seconds. .MONDAY...Northeast wind 20 to 25 kt. Seas 9 to 11 ft. Wave Detail: Northeast 8 ft at 8 seconds, northeast 6 ft at 7 seconds and northeast 3 ft at 12 seconds. .MONDAY NIGHT...Northeast wind 15 to 25 kt. Seas 10 to 11 ft. Wave Detail: East 9 ft at 8 seconds, east 5 ft at 7 seconds and northeast 3 ft at 11 seconds. .TUESDAY...Northeast wind 15 to 20 kt. Seas 8 to 10 ft. Wave Detail: East 8 ft at 9 seconds, northeast 4 ft at 6 seconds, north 4 ft at 9 seconds and northeast 2 ft at 11 seconds. A chance of showers. .WEDNESDAY...Northeast wind 15 to 20 kt. Seas 8 to 9 ft. Wave Detail: East 7 ft at 9 seconds, northeast 4 ft at 6 seconds, north 3 ft at 11 seconds and northeast 2 ft at 10 seconds. A chance of showers. .THURSDAY...Northeast wind 10 to 15 kt. Seas 5 to 7 ft. Wave Detail: East 6 ft at 8 seconds, northeast 3 ft at 5 seconds and north 2 ft at 10 seconds. $$ PMZ151-152-212200- Guam Coastal Waters-Rota Coastal Waters- 450 PM ChST Sat Mar 21 2026 ...SMALL CRAFT ADVISORY IN EFFECT FROM TONIGHT THROUGH SUNDAY AFTERNOON... .TONIGHT...Northeast wind 15 to 20 kt. Seas 7 to 10 ft. Wave Detail: Northeast 7 ft at 8 seconds, northeast 4 ft at 6 seconds, north 5 ft at 13 seconds and northeast 3 ft at 14 seconds. Evening scattered showers across western waters. .SUNDAY...Northeast wind 20 kt. Seas 8 to 10 ft. Wave Detail: Northeast 7 ft at 8 seconds, northeast 5 ft at 6 seconds, north 3 ft at 12 seconds and northeast 3 ft at 14 seconds. .SUNDAY NIGHT...Northeast wind 20 kt. Seas 7 to 9 ft. Wave Detail: Northeast 6 ft at 8 seconds, northeast 5 ft at 6 seconds, northeast 3 ft at 12 seconds and north 2 ft at 11 seconds. .MONDAY...Northeast wind 15 to 25 kt. Seas 7 to 9 ft. Wave Detail: Northeast 7 ft at 8 seconds, northeast 5 ft at 7 seconds and northeast 3 ft at 12 seconds. Scattered showers with isolated thunderstorms. .MONDAY NIGHT...East wind 15 to 20 kt with occasional gusts to 30 kt. Seas 8 to 10 ft. Wave Detail: East 8 ft at 8 seconds, east 5 ft at 7 seconds and northeast 3 ft at 11 seconds. Scattered showers with isolated thunderstorms..TUESDAY...East wind 10 to 20 kt. Seas 7 to 9 ft. Wave Detail: East 7 ft at 9 seconds, north 4 ft at 9 seconds, east 4 ft at 5 seconds and northeast 2 ft at 11 seconds. Scattered showers. .WEDNESDAY...Northeast wind 10 to 15 kt. Seas 5 to 7 ft. Wave Detail: East 5 ft at 8 seconds, northeast 3 ft at 4 seconds, north 3 ft at 11 seconds and northeast 2 ft at 10 seconds. A chance of showers. .THURSDAY...Northeast wind 5 to 15 kt. Seas 4 to 6 ft. Wave Detail: East 5 ft at 8 seconds, northeast 3 ft at 4 seconds and north 2 ft at 10 seconds. $$