


Coastal Waters Forecast
Issued by NWS Boston, MA
Issued by NWS Boston, MA
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471 FZUS51 KBOX 300204 CWFBOX Coastal Waters Forecast for Massachusetts and Rhode Island National Weather Service Boston/Norton MA 1004 PM EDT Mon Sep 29 2025 Coastal waters from the Merrimack River MA to Watch Hill RI out to 25 NM ANZ200-301500- 1004 PM EDT Mon Sep 29 2025 .Synopsis for Massachusetts and Rhode Island coastal waters... Weak high pres builds over the waters this afternoon. A cold front will push S of the waters by late Tue, then strong high pres will build from eastern Canada into New Eng Wed through Fri. This high pres will keep Humberto well offshore, but Humberto will bring increasing southerly swell to the waters Tue and Wed, lingering into Thu, with near gale force NE winds late Tue night into Wed night. $$ ANZ250-301500- Coastal waters east of Ipswich Bay and the Stellwagen Bank National Marine Sanctuary- 1004 PM EDT Mon Sep 29 2025 ...SMALL CRAFT ADVISORY IN EFFECT FROM TUESDAY EVENING THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...W winds 5 to 10 kt. Seas 2 to 4 ft. Wave Detail: SE 4 ft at 14 seconds and SE 3 ft at 10 seconds. .TUE...N winds 10 to 15 kt, becoming NE with gusts up to 20 kt in the afternoon. Seas 3 to 5 ft. Wave Detail: SE 5 ft at 14 seconds and NE 3 ft at 4 seconds. .TUE NIGHT...NE winds 15 to 20 kt, increasing to 20 to 25 kt after midnight. Gusts up to 30 kt. Seas 5 to 7 ft. Wave Detail: NE 7 ft at 6 seconds and SE 4 ft at 15 seconds. .WED...N winds 20 to 25 kt. Gusts up to 30 kt, increasing to 40 kt in the afternoon. Seas 6 to 9 ft. Wave Detail: NE 9 ft at 7 seconds and SE 4 ft at 15 seconds. .WED NIGHT AND THU...NE winds 20 to 25 kt with gusts up to 40 kt. Seas 6 to 9 ft. Wave Detail: NE 9 ft at 7 seconds and SE 5 ft at 15 seconds. .THU NIGHT...E winds 5 to 10 kt, becoming W after midnight. Seas 3 to 5 ft. Wave Detail: E 5 ft at 10 seconds and S 1 foot at 12 seconds. .FRI THROUGH SAT NIGHT...SW winds 5 to 10 kt. Seas 3 to 5 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ251-301500- Massachusetts Bay and Ipswich Bay- 1004 PM EDT Mon Sep 29 2025 ...SMALL CRAFT ADVISORY IN EFFECT FROM TUESDAY EVENING THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...W winds 5 to 10 kt. Seas around 2 ft. Wave Detail: SE 2 ft at 10 seconds and NE 1 foot at 3 seconds. .TUE...N winds 5 to 10 kt, becoming NE 10 to 15 kt with gusts up to 20 kt in the afternoon. Seas 2 to 3 ft. Wave Detail: NE 2 ft at 4 seconds and SE 2 ft at 12 seconds. .TUE NIGHT...NE winds 15 to 20 kt, increasing to 20 to 25 kt after midnight. Gusts up to 30 kt. Seas 2 to 3 ft, building to 3 to 5 ft after midnight. Wave Detail: NE 3 ft at 4 seconds and SE 1 foot at 13 seconds, becoming NE 5 ft at 5 seconds and SE 1 foot at 12 seconds. .WED...N winds 20 to 25 kt with gusts up to 35 kt. Seas 4 to 6 ft. Wave Detail: NE 6 ft at 7 seconds and SE 2 ft at 15 seconds. .WED NIGHT AND THU...NE winds 25 to 30 kt with gusts up to 35 kt. Seas 5 to 7 ft. Wave Detail: NE 7 ft at 8 seconds and N 1 foot at 5 seconds. .THU NIGHT...SE winds around 5 kt, becoming SW around 5 kt after midnight. Seas 2 to 4 ft. Wave Detail: E 4 ft at 9 seconds and S 1 foot at 13 seconds. .FRI THROUGH SAT NIGHT...SW winds 5 to 10 kt. Seas 2 to 4 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ231-301500- Cape Cod Bay- 1004 PM EDT Mon Sep 29 2025 ...GALE WATCH IN EFFECT FROM LATE TUESDAY NIGHT THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...SW winds around 5 kt. Seas around 2 ft. Wave Detail: SE 2 ft at 16 seconds and W 1 foot at 2 seconds. .TUE...NW winds 5 to 10 kt, becoming NE 10 to 15 kt with gusts up to 20 kt in the afternoon. Seas 2 to 3 ft. Wave Detail: SE 3 ft at 15 seconds and N 2 ft at 3 seconds. .TUE NIGHT...NE winds 15 to 20 kt, increasing to 20 to 25 kt after midnight. Gusts up to 30 kt. Seas 3 to 5 ft. Wave Detail: N 5 ft at 5 seconds and SE 3 ft at 16 seconds. .WED...NE winds 20 to 25 kt, becoming N 25 to 30 kt in the afternoon. Gusts up to 40 kt. Seas 4 to 6 ft. Wave Detail: N 6 ft at 5 seconds and SE 3 ft at 15 seconds. .WED NIGHT AND THU...N winds 25 to 30 kt with gusts up to 40 kt. Seas 4 to 6 ft. Wave Detail: N 6 ft at 6 seconds and SE 3 ft at 14 seconds. .THU NIGHT...NE winds 5 to 10 kt, becoming W after midnight. Seas 2 to 4 ft. Wave Detail: E 4 ft at 10 seconds and N 3 ft at 6 seconds. .FRI THROUGH SAT NIGHT...SW winds 5 to 10 kt. Seas 2 to 3 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ254-301500- Coastal waters from Provincetown MA to Chatham MA to Nantucket MA out 20 nm- 1004 PM EDT Mon Sep 29 2025 ...GALE WATCH IN EFFECT FROM LATE TUESDAY NIGHT THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...SW winds around 5 kt. Seas 3 to 5 ft. Wave Detail: SE 5 ft at 16 seconds and SE 2 ft at 11 seconds. .TUE...NW winds 5 to 10 kt, becoming NE 10 to 15 kt with gusts up to 20 kt in the afternoon. Seas 5 to 7 ft. Wave Detail: S 7 ft at 15 seconds and NE 2 ft at 3 seconds. .TUE NIGHT...NE winds 20 to 25 kt, increasing to 25 to 30 kt after midnight. Seas 6 to 9 ft. Wave Detail: NE 8 ft at 6 seconds and S 7 ft at 15 seconds. .WED...NE winds 25 to 30 kt with gusts up to 35 kt. Seas 8 to 11 ft. Wave Detail: NE 10 ft at 8 seconds and S 7 ft at 15 seconds. .WED NIGHT...NE winds 25 to 30 kt with gusts up to 35 kt. Seas 8 to 11 ft. Wave Detail: NE 10 ft at 8 seconds and SE 7 ft at 13 seconds. .THU...NE winds 20 to 25 kt with gusts up to 30 kt. Seas 7 to 10 ft, subsiding to 5 to 8 ft in the afternoon. Wave Detail: NE 9 ft at 8 seconds and SE 3 ft at 12 seconds, becoming NE 8 ft at 9 seconds and SE 3 ft at 11 seconds. .THU NIGHT...NE winds 10 to 15 kt with gusts up to 20 kt, becoming N around 5 kt after midnight. Seas 5 to 7 ft. .FRI AND FRI NIGHT...W winds 5 to 10 kt. Seas 3 to 5 ft. .SAT AND SAT NIGHT...SW winds 5 to 10 kt. Seas 4 to 6 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ255-301500- Coastal Waters extending out to 25 nm South of Marthas Vineyard and Nantucket- 1004 PM EDT Mon Sep 29 2025 ...GALE WATCH IN EFFECT FROM LATE TUESDAY NIGHT THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...S winds around 5 kt, becoming W. Seas 3 to 4 ft, building to 4 to 6 ft. Wave Detail: S 4 ft at 16 seconds and S 2 ft at 6 seconds, becoming S 5 ft at 16 seconds and S 1 foot at 6 seconds. .TUE...N winds 5 to 10 kt, becoming NE 15 to 20 kt in the afternoon. Seas 5 to 7 ft. Wave Detail: S 7 ft at 15 seconds and NE 1 foot at 3 seconds. .TUE NIGHT...NE winds 20 to 25 kt, increasing to 25 to 30 kt with gusts up to 35 kt after midnight. Seas 7 to 10 ft. Wave Detail: NE 8 ft at 6 seconds and S 7 ft at 15 seconds. .WED...NE winds around 30 kt with gusts up to 40 kt. Seas 9 to 12 ft. Wave Detail: N 9 ft at 6 seconds and S 8 ft at 14 seconds. .WED NIGHT...NE winds around 30 kt with gusts up to 40 kt. Seas 9 to 12 ft. Wave Detail: N 9 ft at 7 seconds and S 7 ft at 14 seconds. .THU...NE winds 25 to 30 kt, diminishing to 20 to 25 kt in the afternoon. Seas 7 to 10 ft. Wave Detail: N 9 ft at 6 seconds and E 4 ft at 10 seconds. .THU NIGHT...NE winds 10 to 15 kt with gusts up to 20 kt, becoming N 5 to 10 kt after midnight. Seas 5 to 7 ft. .FRI AND FRI NIGHT...W winds 5 to 10 kt. Seas 3 to 5 ft. .SAT AND SAT NIGHT...SW winds around 10 kt. Seas 4 to 6 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ256-301500- Coastal Waters from Montauk NY to Marthas Vineyard extending out to 20 nm South of Block Island- 1004 PM EDT Mon Sep 29 2025 ...SMALL CRAFT ADVISORY IN EFFECT THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...S winds around 5 kt, becoming W. Seas 4 to 6 ft. Wave Detail: SE 5 ft at 15 seconds and S 2 ft at 6 seconds. .TUE...N winds 5 to 10 kt, becoming NE 15 to 20 kt in the afternoon. Seas 5 to 7 ft. Wave Detail: SE 7 ft at 15 seconds. .TUE NIGHT...NE winds 20 to 25 kt, increasing to 25 to 30 kt after midnight. Seas 6 to 9 ft, building to 8 to 11 ft after midnight. Wave Detail: NE 7 ft at 5 seconds and S 6 ft at 15 seconds, becoming NE 10 ft at 7 seconds and S 6 ft at 15 seconds. .WED...NE winds 25 to 30 kt with gusts up to 35 kt. Seas 9 to 12 ft. Wave Detail: NE 10 ft at 7 seconds and S 7 ft at 14 seconds. .WED NIGHT...NE winds 25 to 30 kt with gusts up to 35 kt. Seas 9 to 12 ft. Wave Detail: N 10 ft at 7 seconds and SE 7 ft at 14 seconds. .THU...NE winds 25 to 30 kt, diminishing to 20 to 25 kt in the afternoon. Seas 7 to 10 ft. Wave Detail: N 9 ft at 6 seconds and SE 6 ft at 11 seconds. .THU NIGHT...NE winds 10 to 15 kt, diminishing to around 5 kt after midnight. Seas 5 to 7 ft. .FRI AND FRI NIGHT...W winds 5 to 10 kt, increasing to 10 to 15 kt. Seas 3 to 5 ft. .SAT...W winds around 10 kt. Seas 4 to 6 ft. .SAT NIGHT...SW winds around 10 kt. Seas 3 to 5 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ232-301500- Nantucket Sound- 1004 PM EDT Mon Sep 29 2025 ...GALE WATCH IN EFFECT FROM LATE TUESDAY NIGHT THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...SW winds around 5 kt. Seas 2 to 3 ft. Wave Detail: SE 2 ft at 17 seconds and NE 1 foot at 4 seconds. .TUE...NW winds 5 to 10 kt, becoming NE 15 to 20 kt with gusts up to 25 kt in the afternoon. Seas 2 to 4 ft. Wave Detail: S 3 ft at 15 seconds and NE 2 ft at 3 seconds. .TUE NIGHT...NE winds 20 to 25 kt, increasing to 25 to 30 kt with gusts up to 35 kt after midnight. Seas 4 to 6 ft. Wave Detail: NE 5 ft at 5 seconds and S 3 ft at 15 seconds. .WED...NE winds 25 to 30 kt with gusts up to 40 kt. Seas 5 to 7 ft. Wave Detail: N 6 ft at 5 seconds and S 3 ft at 14 seconds. .WED NIGHT...NE winds 25 to 30 kt with gusts up to 35 kt. Seas 5 to 7 ft. Wave Detail: N 6 ft at 5 seconds and S 3 ft at 14 seconds. .THU...NE winds 25 to 30 kt, diminishing to 20 to 25 kt in the afternoon. Seas 4 to 6 ft. Wave Detail: N 6 ft at 5 seconds and E 2 ft at 10 seconds. .THU NIGHT...NE winds 10 to 15 kt with gusts up to 20 kt, becoming N around 5 kt after midnight. Seas 3 to 5 ft, subsiding to 2 to 3 ft after midnight. .FRI THROUGH SAT NIGHT...SW winds 10 to 15 kt. Seas 2 to 3 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ233-301500- Vineyard Sound- 1004 PM EDT Mon Sep 29 2025 ...GALE WATCH IN EFFECT FROM LATE TUESDAY NIGHT THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...SW winds around 5 kt. Seas 2 to 3 ft. Wave Detail: S 3 ft at 16 seconds and S 1 foot at 6 seconds. .TUE...N winds 5 to 10 kt, becoming NE 10 to 15 kt with gusts up to 20 kt in the afternoon. Seas 2 to 4 ft. Wave Detail: S 4 ft at 15 seconds and NE 2 ft at 3 seconds. .TUE NIGHT...NE winds 15 to 20 kt, increasing to 20 to 25 kt after midnight. Gusts up to 30 kt. Seas 4 to 6 ft. Wave Detail: NE 4 ft at 4 seconds and S 4 ft at 15 seconds. .WED...NE winds 25 to 30 kt with gusts up to 35 kt. Seas 4 to 6 ft. Wave Detail: N 4 ft at 4 seconds and S 4 ft at 14 seconds. .WED NIGHT...NE winds 20 to 25 kt with gusts up to 30 kt. Seas 4 to 6 ft. Wave Detail: N 4 ft at 5 seconds and S 4 ft at 14 seconds. .THU...NE winds 15 to 20 kt with gusts up to 25 kt. Seas 3 to 5 ft. Wave Detail: N 3 ft at 5 seconds and SE 2 ft at 12 seconds. .THU NIGHT...NE winds 10 to 15 kt, becoming N around 5 kt after midnight. Seas 2 to 4 ft. .FRI THROUGH SAT NIGHT...SW winds 10 to 15 kt. Seas 2 to 3 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ234-301500- Buzzards Bay- 1004 PM EDT Mon Sep 29 2025 ...GALE WATCH IN EFFECT FROM LATE TUESDAY NIGHT THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...SW winds around 5 kt. Seas 2 to 3 ft. Wave Detail: S 2 ft at 16 seconds and NE 1 foot at 3 seconds. .TUE...N winds 5 to 10 kt, becoming NE 15 to 20 kt with gusts up to 25 kt in the afternoon. Seas 2 to 4 ft. Wave Detail: S 3 ft at 15 seconds and NE 2 ft at 3 seconds. .TUE NIGHT...NE winds 15 to 20 kt, increasing to 20 to 25 kt after midnight. Gusts up to 30 kt. Seas 2 to 4 ft. Wave Detail: NE 3 ft at 4 seconds and S 3 ft at 15 seconds. .WED...N winds 25 to 30 kt with gusts up to 35 kt. Seas 4 to 6 ft. Wave Detail: N 4 ft at 5 seconds and S 3 ft at 14 seconds. .WED NIGHT...NE winds 20 to 25 kt with gusts up to 35 kt. Seas 3 to 5 ft. Wave Detail: N 4 ft at 5 seconds and SE 3 ft at 11 seconds. .THU AND THU NIGHT...NW winds 15 to 20 kt with gusts up to 25 kt. Seas 2 to 4 ft. Wave Detail: N 3 ft at 5 seconds and SE 2 ft at 12 seconds. .FRI THROUGH SAT NIGHT...SW winds 10 to 15 kt. Seas around 2 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ235-301500- Rhode Island Sound- 1004 PM EDT Mon Sep 29 2025 ...SMALL CRAFT ADVISORY IN EFFECT FROM 4 AM EDT TUESDAY THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...W winds around 5 kt. Seas 3 to 5 ft. Wave Detail: S 5 ft at 16 seconds and S 2 ft at 6 seconds. .TUE...N winds 5 to 10 kt, becoming NE 10 to 15 kt with gusts up to 20 kt in the afternoon. Seas 4 to 6 ft. Wave Detail: S 6 ft at 15 seconds and NE 1 foot at 3 seconds. .TUE NIGHT...NE winds 20 to 25 kt, increasing to 25 to 30 kt after midnight. Seas 5 to 8 ft. Wave Detail: NE 6 ft at 5 seconds and S 6 ft at 15 seconds. .WED...NE winds 25 to 30 kt with gusts up to 35 kt. Seas 6 to 9 ft. Wave Detail: NE 7 ft at 5 seconds and S 7 ft at 14 seconds. .WED NIGHT...NE winds 20 to 25 kt with gusts up to 30 kt. Seas 6 to 9 ft, subsiding to 5 to 7 ft after midnight. Wave Detail: N 6 ft at 5 seconds and S 6 ft at 14 seconds, becoming N 6 ft at 5 seconds and SE 5 ft at 17 seconds. .THU...NE winds 20 to 25 kt, diminishing to 15 to 20 kt in the afternoon. Seas 4 to 6 ft. Wave Detail: N 6 ft at 5 seconds and SE 3 ft at 12 seconds. .THU NIGHT...NE winds 10 to 15 kt, becoming N around 5 kt after midnight. Seas 3 to 5 ft. .FRI THROUGH SAT NIGHT...SW winds 5 to 10 kt. Seas 2 to 4 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ237-301500- Block Island Sound- 1004 PM EDT Mon Sep 29 2025 ...SMALL CRAFT ADVISORY IN EFFECT FROM 4 AM EDT TUESDAY THROUGH LATE WEDNESDAY NIGHT... .OVERNIGHT...W winds around 5 kt. Seas 2 to 4 ft. Wave Detail: SE 4 ft at 16 seconds and S 1 foot at 6 seconds. .TUE...N winds 5 to 10 kt, becoming NE 10 to 15 kt with gusts up to 20 kt in the afternoon. Seas 4 to 6 ft. Wave Detail: SE 6 ft at 15 seconds. .TUE NIGHT...NE winds 15 to 20 kt, increasing to 20 to 25 kt after midnight. Gusts up to 30 kt. Seas 5 to 8 ft. Wave Detail: NE 6 ft at 6 seconds and SE 6 ft at 15 seconds. .WED...NE winds 20 to 25 kt with gusts up to 30 kt. Seas 6 to 9 ft. Wave Detail: NE 6 ft at 6 seconds and S 6 ft at 14 seconds. .WED NIGHT...NE winds 20 to 25 kt with gusts up to 30 kt. Seas 6 to 9 ft. Wave Detail: NE 6 ft at 6 seconds and SE 6 ft at 14 seconds. .THU...NE winds 15 to 20 kt, diminishing to 10 to 15 kt in the afternoon. Gusts up to 25 kt. Seas 5 to 7 ft. Wave Detail: NE 5 ft at 6 seconds and SE 3 ft at 12 seconds. .THU NIGHT...NE winds 5 to 10 kt, becoming N after midnight. Seas 3 to 5 ft. .FRI THROUGH SAT NIGHT...SW winds 5 to 10 kt. Seas 2 to 4 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ230-301500- Boston Harbor- 1004 PM EDT Mon Sep 29 2025 .OVERNIGHT...W winds around 5 kt. Waves 1 foot or less. .TUE...N winds 5 to 10 kt, becoming NE 10 to 15 kt with gusts up to 20 kt in the afternoon. Waves around 2 ft. .TUE NIGHT...NE winds 10 to 15 kt, increasing to 15 to 20 kt after midnight. Gusts up to 25 kt. Waves 2 to 3 ft. .WED...N winds 15 to 20 kt with gusts up to 25 kt. Waves 2 to 3 ft. .WED NIGHT AND THU...NE winds 15 to 20 kt with gusts up to 25 kt. Waves 2 to 3 ft. .THU NIGHT...SE winds around 5 kt, becoming SW around 5 kt after midnight. Waves 1 foot or less, except 2 to 4 ft at the outer harbor entrance. .FRI THROUGH SAT NIGHT...SW winds 5 to 10 kt. Waves 1 foot or less. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ ANZ236-301500- Narragansett Bay- 1004 PM EDT Mon Sep 29 2025 .OVERNIGHT...W winds around 5 kt. Waves 2 to 3 ft. .TUE...N winds 5 to 10 kt, becoming NE 10 to 15 kt with gusts up to 20 kt in the afternoon. Waves 2 to 3 ft. .TUE NIGHT...NE winds 10 to 15 kt, becoming N 15 to 20 kt after midnight. Gusts up to 25 kt. Waves 2 to 3 ft, except 4 to 6 ft at the bay entrance. .WED...N winds 15 to 20 kt, becoming NE 20 to 25 kt in the afternoon. Gusts up to 30 kt. Waves 2 to 3 ft, except 4 to 6 ft at the bay entrance. .WED NIGHT AND THU...NE winds 15 to 20 kt with gusts up to 25 kt. Waves 2 to 3 ft, except 4 to 6 ft at the bay entrance. .THU NIGHT...NE winds 5 to 10 kt, becoming NW after midnight. Waves 2 to 3 ft. .FRI THROUGH SAT NIGHT...SW winds 5 to 10 kt. Waves 2 to 3 ft. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height. $$ For the latest updates...please visit our webpage at www.weather.gov/boston You can follow us on Facebook at www.facebook.com/NWSBoston You can follow us on Twitter at @NWSBoston