Boston Harbor Marine Forecast
| Overnight...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt, Becoming N 5 To 10 Kt. Waves 1 Foot Or Less. |
| Tue...E Winds 5 To 10 Kt. Waves 1 Foot Or Less, Then Around 2 Ft In The Afternoon. |
| Tue Night...E Winds 5 To 10 Kt. Waves 1 Foot Or Less. |
| Wed...Se Winds 5 To 10 Kt. Waves 1 Foot Or Less. |
| Wed Night...Se Winds 5 To 10 Kt. Waves 1 Foot Or Less. A Chance Of Showers. |
| Thu And Thu Night...S Winds Around 5 Kt. Waves 1 Foot Or Less. A Chance Of Showers. |
| Fri...S Winds 5 To 10 Kt. Waves 1 Foot Or Less. |
| Fri Night...Sw Winds 5 To 10 Kt. Waves 1 Foot Or Less. A Chance Of Showers. |
| Sat...S Winds 5 To 10 Kt. Waves 1 Foot Or Less. A Chance Of Showers. |
| Sat Night...Sw Winds Around 10 Kt. Waves 1 Foot Or Less. Showers Likely. 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 733pm EDT Monday May 12 2025 Synopsis A weak backdoor cold front will drop south through New England late tonight as high pressure remains over the Maritimes through Wednesday. Low pressure over the Carolinas Wednesday will weaken as it approaches the Northeast Thursday and Friday, then a cold front should cross the region Saturday. Near Term - Through Tuesday Updated 130pm Mon Key Message: * Continued dry but cooler near coast Tue. Our area remains under influence of NW-SE oriented ridge from Great Lakes to Mid Atlantic with one upper low over Maritimes and another across southeastern states. This pattern stays locked in through Tuesday but a weak backdoor front will drop south through New England, either dissipating or pushing south of New England Tuesday morning. Its only effect will be a wind shift to NE, and with high pressure remaining offshore and a weak gradient, onshore flow Tuesday will bring cooler temps to locations near coast while interior areas have another day of above normal temps. Short Term - Tuesday Night Updated 130pm Mon Key Message: * Few showers possible late Tuesday night in western MA/CT. Ridge axis slowly shifts into northern New England as upper low over Maritimes exits region. This will also allow the other closed low over Carolinas to begin to eject northward, but plenty of dry air should remain over SNE to limit northward extent of any showers. It's possible we see a few showers sneak into western parts of MA/CT late Tuesday night but that could end up just being a few sprinkles or brief showers from a mid level cloud deck. Long Term - Wednesday Through Monday Updated 130pm Mon Key Messages: * Pattern turns warmer/more humid into weekend. * Best chances for showers/storms Fri and Sat. Seeing good agreement among longer range guidance which gives us higher confidence in overall pattern. Weakening upper low from the south opens up over Northeast later this week as it runs up into upper ridging that shifts into Maritimes, and is eventually kicked out by a stronger northern stream closed low which tracks across southern Canada. Increasing southerly flow aloft will result in at least a few showers in Wed-Thu timeframe. We should see more instability and stronger dynamics ahead of cold front in Fri-Sat timeframe when showers/storms should be more numerous. CSU ML guidance also shows a low risk of severe storms both days but pattern doesn't look to favorable here in SNE and higher odds are certainly farther W and SW of our region - something to monitor in coming days. Later in weekend, broad upper trough remains in place which should bring at least diurnal clouds if not a few showers, and onshore flow should also bring cooler temperatures (closer to average for mid May). Marine Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Updated 130pm Mon Overall high confidence through late in the week. Decided to hoist SCAs (Small Craft Advisories) for Boston Harbor and most of E MA waters for 25kt gusts through early this evening based upon seeing deeper mixing aloft on forecast soundings. Probably marginal for most but confidence is higher around Cape Cod and Islands, especially near shore. Weak backdoor front drops south later tonight which shifts winds to N/NW, then onshore winds (mainly E/NE) expected Tuesday and Tue night but winds and seas stay well below SCA. Later in week, low pressure over Carolinas weakens as it approaches Northeast Thu-Fri. Outlook /Wednesday through Saturday/... Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Wednesday Night through Thursday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, isolated thunderstorms. Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...None. RI...None. Marine Small Craft Advisory until 8pm EDT this evening for ANZ230. Small Craft Advisory until 9pm EDT this evening for ANZ231>234-250-254-255. |
Boston MA Radar
Northeast Radar
East Coast Satellite