Boston Harbor Marine Forecast
| Today...N Winds Around 5 Kt, Becoming Se This Afternoon. Waves 1 Foot Or Less. |
| Tonight...S Winds 5 To 10 Kt. Waves 1 Foot Or Less. |
| Mon...Sw Winds 5 To 10 Kt, Increasing To 10 To 15 Kt In The Afternoon. Waves 1 Foot Or Less, Then Around 2 Ft In The Afternoon. |
| Mon Night...Sw Winds 10 To 15 Kt. Waves Around 2 Ft. |
| Tue...Sw Winds 10 To 15 Kt, Increasing To 15 To 20 Kt In The Afternoon. Gusts Up To 25 Kt. Waves Around 2 Ft. |
| Tue Night...Sw Winds 15 To 20 Kt With Gusts Up To 25 Kt. Waves Around 2 Ft. A Chance Of Showers In The Evening, Then Showers After Midnight With Vsby 1 To 3 Nm. |
| Wed...Nw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Waves Around 2 Ft. Showers. Vsby 1 To 3 Nm. |
| Wed Night...N Winds 10 To 15 Kt With Gusts Up To 20 Kt. Waves Around 2 Ft. A Chance Of Showers. |
| Thu And Thu Night...N Winds 10 To 15 Kt With Gusts Up To 20 Kt, Diminishing To 5 To 10 Kt. Waves Around 2 Ft, Then 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. |
| Area Forecast Discussion National Weather Service Boston/Norton MA 302am EDT Sunday Oct 5 2025 Synopsis A ridge of high pressure in control of our weather will continue to bring dry and unseasonably warm afternoon temperatures through Tuesday. A cold front moves through Southern New England Tuesday night into Wednesday, bringing rain and much cooler/drier weather for Thursday and Friday. Near Term - Until 6pm This Evening 250am Update: Key Messages: * Another very warm day with seabreezes near the coasts. * Highs in the low to mid 80s inland, and in the mid 70s for the eastern and southern coasts. Details: High pressure remains parked over the mid-Atlantic coastal waters, while the axis of an amplified mid-upper level ridge extends from VA northward up to western NY. Thus the main drivers for our weather pattern for today are little changed compared to yesterday. Winds are essentially nil with current temps running rather mild for an early October evening, in the lower 50s to around 60. In addition...while still tolerable, dewpoints have started to rise into the 50s (to spot 60 degree readings along the immediate southeast coast). Offered a persistence forecast for today with not much overall change to the weather pattern from 24 hrs ago. We are again expecting another warm and dry day with plenty of sun, leading to well above normal temperatures. Weak pressure gradient and boundary layer winds will favor seabreezes on the southern and eastern coasts, keeping these areas slightly cooler compared to inland. Highs in the mid 70s along the coasts, with inland highs in the low to mid 80s. As was the case yesterday, have to watch for a late-day high along the eastern MA coast once the seabreeze shuts off and becomes a landbreeze. Short Term - 6pm This Evening Through Monday Night 250am Update: Key Messages: * Mostly clear for most tonight thru Mon, but have to watch for fog/low clouds overnight tonight in southeast New England. If it develops, it may linger into a good part of Monday along the immediate south coast. * Highs again in the lower 80s Mon, but in the lower 70s along the south coast. Details: Tonight: Dry weather and mostly clear skies are again expected for tonight for a large portion if not all of Southern New England. Where there is now some uncertainty in the forecast is along the South Coast, Cape and Islands and possibly into portions of CT. Dewpoints come up a bit (into the lower 60s) on a light SW wind, and the NAM-based guidance in particular hits these areas hard with fog and stratus for the overnight, as this shallow layer of moisture becomes trapped under the strong subsidence inversion. The GFS (Global Forecast System) on the other hand is clear and dry. NAM has a tendency (a bias) to overdo shallow moist layers so it's tough to place much faith in that outcome; but I did side the forecast that way by introducing patchy fog and partly cloudy skies for parts of CT-RI-SE MA. While not likely a major issue for the overnight...if it does develop, it would cast some question on the forecast for these same areas for Monday. Otherwise, it's another rather mild night with lows in the 50s to near 60. Monday and Monday Night: SWly winds start to pick up further on Mon, and we expect another day of above normal temperatures under full sun for a large portion of Southern New England. Mixing looks shallow so that should limit gusts to no more than 20 mph but with sustained SW winds around 10 mph. The uncertainty in the forecast revolves around how quickly might stratus and fog in southeast/southern-coastal New England disperses, if it indeed developed overnight tonight. That this moisture is trapped underneath an inversion suggests it may be slower to scour out and/or retreat to the cooler ocean waters. These areas probably end up cooler than further inland anyway given the SW breeze, but raw 2-m AGL temperature output from the NAM/NAM-3km show areas such as New Bedford, Newport and the Cape struggling to reach 70 degrees. Though we're looking at low to mid 80s high temps away from the southern for most; for southeast New England I kept a mention of partial cloud cover and opted for highs in the lower 70s, with eyes toward bumping these back up a few degrees if low clouds scatter out sooner. Remains mild for the evening too, especially with the continued southerly breeze. We'll have to monitor if south-coastal fog/stratus re-develops toward the coast, but its extent could be more limited by stronger SW breezes. Lows mid 50s to the lower 60s. Long Term - Tuesday Through Saturday Key Messages: * Above normal temps and breezy for Tue, though not as warm as prior days. * Much needed rains Tuesday night into Wednesday as a cold front moves in, though not enough to break the drought. * Cooler, dry and blustery Wednesday night, with cooler temps for Thurs. * Modifying temps Fri into the weekend, but drier weather generally prevails. Details: Tuesday: Tuesday still looks to be another day with above-normal temperatures particularly inland, but may end up slightly cooler than prior days as cloud cover begins to increase during the afternoon ahead of a cold front. It also turns rather breezy with SWly gusts in the 20 to as much as 30 mph range. Though RHs are on the high side, that we've had several days of antecedent dryness could still support fire weather concerns on Tue. Highs mainly in the 70s to a few lower 80s. Tuesday Night and Wednesday: A cold front will be slowly traversing through Southern New England Tuesday night into Wed, bringing a much-needed rainfall to our area. The exact timing of the front is still a little uncertain, though the current indications indicate rain beginning as soon as the pre-dawn hrs in far western MA/CT and mainly during the daytime hours Wed. Global ensemble Quantitative Precipitation Forecast probabilities remain less bullish on rainfall than the deterministic guidance does, but the odds for a wetting rainfall are increasing. Thunder could be possible but the unfavorable time-of-day could limit any thunder potential to a weak mid-level instability burst and not likely be supportive of strong storms. This front looks to take most of Wednesday to reach the coastline, before rapid drying takes place to go along with strong Cold Air Advection and increasing NWly gusts. Mild lows Tuesday night with overcast and SW breezes in the upper 50s to the mid 60s, then only climbing a few degrees (mid 60s to near 70) Wednesday before temps rapidly cool off late in the day. Wednesday Night through Thursday: Much cooler temperatures and drier weather then settles in for late in the week, as a strong 1030+ mb high pressure area builds into New England. Strongest cold advection takes place Wednesday night (our 925 mb temps plummet to around +2 to +4C by Thu AM), supporting a rather chilly night but seems that northerly breezes prevail for most areas and that could preclude frost from developing. While sunny, Thurs is a cooler day with decreasing northerly winds, with highs in the 50s to lower 60s. Though our low-level temps modify into Thurs night, strongest radiational cooling takes place then, and temps could support a frost in some areas in mid 30s to lower 40s. Friday into Next Weekend: Gradually modifying temps into Fri as high pressure maintains itself. Some uncertainty for next weekend as some global ensemble members show some developing troughing over the waters, and potential for clouds and light showers for the weekend, but this outcome seems to be in the minority compared to an otherwise drier model-consensus. Marine Forecaster Confidence Levels... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Through Monday Night: High confidence. Winds and seas below small craft advisory levels. Light southerly winds today, increasing to around 10 kt tonight, then increase to around 15-20 kt Mon. Seas mainly 3 ft or less all waters. Areas of marine fog possible tonight which could reduce visbys to one-half mile, and may be slower to disperse into Mon. Outlook /Tuesday through Thursday/... Tuesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas locally approaching 5 ft. Tuesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers. Wednesday: Winds less than 25 kt. Seas up to 5 ft. Rain showers. Local visibility 1 to 3 nm. Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of rain showers. Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...None. RI...None. Marine None. |
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