Boston Harbor Marine Forecast
| This Afternoon...Nw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Waves Around 2 Ft. |
| Tonight...Nw Winds 5 To 10 Kt. Waves Around 2 Ft In The Evening, Then 1 Foot Or Less. |
| Mon...W Winds Around 5 Kt, Becoming Se In The Afternoon. Waves 1 Foot Or Less. |
| Mon Night...S Winds 5 To 10 Kt. Waves 1 Foot Or Less. |
| Tue...S Winds 5 To 10 Kt, Becoming Se 10 To 15 Kt With Gusts Up To 20 Kt In The Afternoon. Waves 2 To 3 Ft. |
| Tue Night...S Winds 10 To 15 Kt. Gusts Up To 20 Kt In The Evening. Waves 2 To 3 Ft. Showers. A Chance Of Tstms In The Evening. |
| Wed And Wed Night...Sw Winds 10 To 15 Kt, Becoming W. Gusts Up To 25 Kt. Waves Around 2 Ft. Showers Likely With A Chance Of Tstms. |
| Thu And Thu Night...Sw Winds 5 To 10 Kt. Waves 1 Foot Or Less. Winds And Waves Higher In And Near Tstms. 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. |
| Area Forecast Discussion National Weather Service Boston/Norton MA 205pm EDT Sunday July 19 2026 .WHAT HAS CHANGED... No changes were made during this forecast update. .KEY MESSAGES... - Breezy and comfortable this afternoon and Monday. A high risk of rip currents continues through this evening on south-facing beaches. - Periods of rain, perhaps heavy at times possible later Tuesday into Wednesday. Higher confidence in a period of impactful marine weather during that timeframe. - Drying out Thursday. Mainly dry through next weekend. Near to slightly below normal temperatures. KEY MESSAGE 1...Breezy and comfortable this afternoon and Monday. A high risk of rip currents continues through this evening on south- facing beaches. Full sun today as lingering smoke and haze finally pushes south of the region under deep northwest flow. Seeing much better air quality this afternoon as most of the lingering smoke remains aloft compared to yesterday. PM2.5 values remain elevated, generally in the 50-70 ug/m3 range, which is still impactful for sensitive groups. Much cooler aloft today behind a strong cold front with 850 mb temps in the upper single digits to low teens. Should still be quite mild with mid-July sun angle and downsloping supporting highs in the upper 70s to lower/mid 80s. Other story today is the continued risk for rip currents along the south coast. Buoys show widespread swells between 4 and 7 feet from the waters S of Rhode Island to the entrance of the Buzzards Bay. Elevated swells continue through the rest of the day and help to keep the rip current risk high from Rhode Island to the Cape and Islands this afternoon and evening. Elsewhere, there is a moderate risk for rip currents That's the only fly in the ointment though. Not sure if today qualifies as the pick of summer 2026, but it's certainly in the running. Enjoy! It's a cool and pleasant night tonight as high pressure crests over the region. Mainly clear skies allow lows to cool into the mid 50s for most locations with strong radiational cooling. Weak southwest return flow becomes established on Monday as high pressure pulls offshore. The weak advection warms 850 mb temps to +11-12C translating to temperatures about 3-5 degrees warmer than today. KEY MESSAGE 2...Periods of rain, perhaps heavy at times possible later Tuesday into Wednesday. Higher confidence in a period of impactful marine weather during that timeframe. Confidence is increasing in another period of unsettled weather and even the potential for areas of heavy rainfall late Tuesday into Wednesday. A strong disturbance located in the left-exit region of a moderately strong (100-110 kt) jet approaches the region from the upper Midwest Tuesday afternoon. Closer to the surface, strong low- level southerly flow advects copious amounts of tropical moisture into the region. By Tuesday afternoon, guidance shows PWAT (Precipitable Water) values increasing to >2". Still seeing a signal for strong low-level moisture convergence over the region Tuesday and Tuesday night on global guidance suggesting the possibility for periods of heavy rainfall. Could even see some thunderstorms with elevated K-index values, though surface instability will likely be limited by dense cloud cover. NBM Quantitative Precipitation Forecast probabilities show mean 24 hour rainfall totals of 1.25-1.75" with the highest probs of 24-hour total rains of an inch or greater over southeast New England, and even low to moderate (30-50%) probs of 2-inch 24 hr totals. Wind fields also improve too, but it's debatable if that translates to severe weather, as most of the machine learning progs don't offer much potential. By Wed, more instability type showers and storms are favored underneath the upper trough before it begins to pull away later Wed/Wednesday night. Will also make a mention for mariners/beachgoers that southwest winds pick up substantially Tuesday night and Wed; ensemble 34-kt wind progs out on the waters are in the 40-70% range so it's very possible gale watches could be needed in the coming days. Seas expected to build and become rough, reaching upwards of 12 ft on the southern outer waters, so that could support a need for high surf headlines for south-facing beaches in the coming days too. KEY MESSAGE 3...Drying out Thursday. Mainly dry through next weekend. Near to slightly below normal temperatures. Latest guidance suite was in reasonable agreement with the evolution of the overall synoptic pattern next week. That said, the usual timing and magnitude differences are present, leading to an average confidence in the forecast details. A cold front may be lingering near the coast in the morning, before finally getting push well out to sea by a high pressure over the Midwest. This high pressure should then arrive by Friday and remain overhead through next weekend. Any lingering morning showers Thursday should be offshore by afternoon. The dry conditions should prevail most of the time through next weekend. Not anticipating it to be overly humid, with temperatures near to slightly below normal. Marine Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. SCAs (Small Craft Advisories) continue for the outer waters today as winds shift to NW with gusts in the 25 to possibly 30 kt range early, but then gradually decrease into the afternoon. Seas 4-7 ft which will be slowly decreasing this evening into the overnight. NW winds decrease tonight to 10 kt or less. Good boating weather Monday as winds turn SW around 10-15 kt. Outlook /Tuesday through Friday/... Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, slight chance of thunderstorms. Tuesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Rain showers, chance of thunderstorms. Wednesday: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 14 ft. Rain showers likely, chance of thunderstorms. Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 14 ft. Chance of rain showers, slight chance of thunderstorms. Thursday: Winds less than 25 kt. Rough seas up to 10 ft. Chance of rain showers. Thursday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Friday: Winds less than 25 kt. Seas up to 5 ft. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...High Risk for Rip Currents until 8pm EDT this evening for MAZ020- 022>024. RI...High Risk for Rip Currents until 8pm EDT this evening for RIZ006>008. Marine Small Craft Advisory until 8pm EDT this evening for ANZ254>256. |
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