Boston Harbor Marine Forecast
| This Afternoon...W Winds Around 5 Kt. Waves 1 Foot Or Less. Areas Of Fog. A Slight Chance Of Showers. Vsby 1 To 3 Nm. |
| Tonight...W Winds Around 5 Kt. Waves 1 Foot Or Less. Areas Of Fog After Midnight With Vsby 1 To 3 Nm. |
| Tue...Sw Winds Around 5 Kt, Becoming S In The Afternoon. Waves 1 Foot Or Less, Then Around 2 Ft In The Afternoon. |
| Tue Night...Sw Winds 10 To 15 Kt. Waves Around 2 Ft. |
| Wed...W Winds Around 10 Kt. Waves 1 Foot Or Less, Then Around 2 Ft In The Afternoon. A Chance Of Showers In The Afternoon. |
| Wed Night...Nw Winds 5 To 10 Kt. Waves 1 Foot Or Less. A Chance Of Showers In The Evening. |
| Thu...N Winds Around 10 Kt. Waves Around 2 Ft. A Chance Of Showers. |
| Thu Night...N Winds 5 To 10 Kt. Waves 1 Foot Or Less. |
| Fri And Fri Night...Ne Winds 5 To 10 Kt, Becoming Sw. Waves 1 Foot Or Less. A Chance Of Showers. 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 159pm EDT Monday May 25 2026 .WHAT HAS CHANGED... No significant changes. .KEY MESSAGES... - Showers fill back in this morning with brief downpours and a thunderstorm possible, transitions to drier weather in the mid to late afternoon from west to east. Warmer and more humid today with partial sunshine late. - Above normal temperatures for the middle of next week before trending closer to normal late next week. A couple periods of showers possible, but no washouts expected. KEY MESSAGE 1...Showers fill back in this morning with brief downpours and a thunderstorm possible, transitions to drier weather in the mid to late afternoon from west to east. Warmer and more humid today with partial sunshine late. Warm front continues to approach from the south and will bring a brief surge of especially warm and moist air with dewpoints into the upper 50s to low 60s over southeastern SNE as the low lifts north directly overhead. Plenty of moisture in the warm sector when eventually the cold front drops through later this morning leading to another surge of rain showers and even some thunderstorms over the south coast where a few hundred J/kg of CAPE will briefly move overhead. This may lead to localized higher amounts of rain under any brief convection. Quickly, though, winds turn out of the west then northwest pulling in much drier air as PWATs (Precipitable Waters) drop quickly behind the frontal passage generally 18-00z. Given slowly clearing skies and potential for lingering high clouds, as mentioned yesterday, some locations could see a good sunset tonight. While most parts of SNE will see showers continuing through around noon (west) to mid afternoon (east) we will have a respite from the cold of yesterday as warm advection leads to temperatures around 15 degrees warmer than yesterday, in the low to mid 70s. Warmest spots will be the CT valley where skies clear soonest and west flow provides a downslope component. KEY MESSAGE 2...Above normal temperatures for the middle of next week before trending closer to normal late next week. A couple periods of showers possible, but no washouts expected. Not much change to the expected overall mid level synoptic pattern from yesterday. However, considerable differences remain between the deterministic models after Wednesday. Thus, have low confidence in the details late next week into next weekend. Will be relying more on ensembles and focusing more on the trends until greater clarity develops. Expecting well above normal temperatures to be in place Tuesday into Wednesday. While we should be on the backside of a cold front for Thursday, there are signals in the NAEFS and NationalBlend that the lower temperatures for Thursday could still turn out to be slightly above normal for late May, with the near to slightly below normal temperatures hold off until Friday into next weekend. Given the uncertainty at this time range, anticipating this timing part of the forecast is likely to change over the coming week. Rainfall-wise, it is very difficult to pin down specific windows of time when the risk for showers is greatest. We can't seem to get sufficient moisture aligned with lift. The synoptic pattern suggests that Wednesday still has potential to be one of those periods as a cold front should be crossing our region. However, the ensembles started to dry out the atmosphere a little more, meaning that shower coverage could be less than previously anticipated. For Thursday, the cooler conditions means increased relative humidity, but there is not much organized lift to focus it. Perhaps colder air aloft could trigger diurnal showers, but the timing of this colder air is questionable. These issues continue right into next weekend with the potential approach of a low pressure. Again, anticipating this aspect of the forecast is likely to undergo changes as this week progresses. Marine Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Monday Night through Thursday...High confidence. Marginal Small Craft Advisory conditions continue tonight across the outer ocean waters, with seas of 4 to 6 ft. These seas gradually subside by daybreak Tuesday, followed by generally tranquil boating conditions through Thursday, with seas mainly 2 to 4 ft. Winds remain light and somewhat variable on Tuesday as high pressure moves overhead. By Wednesday, winds become more southwesterly around 15 kt, with occasional gusts up to 20 kt possible over the nearshore waters south of the coast. While conditions appear marginal, there is a low chance of localized stronger gusts that could warrant a brief Small Craft Advisory. Given the start of the boating season, this potential bears monitoring despite the marginal setup. Heading into Thursday, winds shift more ENE to NE. Both Wednesday and Thursday afternoons feature the chance for isolated pop-up showers or thunderstorms, though a washout is not expected. Outlook /Thursday Night through Saturday/... Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Isolated rain showers, isolated thunderstorms. Wednesday Night through Thursday: Winds less than 25 kt. Isolated rain showers, isolated thunderstorms. Thursday Night through Friday: Winds less than 25 kt. Slight chance of rain showers. Friday Night: Winds less than 25 kt. Chance of rain showers. Saturday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...None. RI...None. Marine Small Craft Advisory until 8am EDT Tuesday for ANZ250-254>256. |
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