Weather for New England and the Northeast

**Area Forecast Discussion, National Weather Service Boston/Norton MA,
353 PM EDT Sun Sep 20 2026**

**What has Changed**

A Gale Watch has been issued for portions of the southern ocean waters from Tuesday afternoon into Thursday.

**Key Messages**

* Light rain continues this afternoon into early Monday morning. Monday afternoon will be breezy, cloudy, and cooler.

* Dry and cool conditions are expected through midweek. Forecasters are watching the potential for a coastal low to develop during the middle to latter part of the week, bringing the possibility of strong winds and rainfall heading into the weekend.

**Discussion**

**Key Message 1, Light rain tonight, followed by a cool and breezy Monday**

A raw, cool, and rainy afternoon continues across southern New England, with rain persisting through much of the evening. The rain will be primarily stratiform, meaning it will be widespread and steady rather than coming from individual thunderstorms, with generally light and occasionally moderate rainfall rates. A rumble of thunder cannot be completely ruled out near the south coast, although the risk is quite low.

Additional rainfall amounts of 0.25 to 0.75 inch are expected, with some localized variation. Flooding is not a concern with this event. Rain will gradually shift offshore overnight and should end by or before daybreak Monday. Conditions will remain raw and wet overnight, with lows in the upper 40s to lower 50s and breezy northerly winds.

On Monday, showers will linger just offshore along a frontal boundary while strong high pressure, around 1030 millibars, builds in from the northwest. This will tighten the pressure gradient, which means the difference in air pressure across the region will increase and produce stronger winds. Breezy north-northeast winds are expected throughout the day, especially near the coast where gusts could reach 20 to 25 mph.

Clouds will remain stubborn for much of the day, although there may be a few breaks of sunshine. Temperatures will remain cool, with highs mainly in the 60s. Clouds will continue Monday night, with lows falling into the 40s across much of the region and remaining in the lower 50s in the urban centers.

**Key Message 2, Dry and cool through midweek, with a potential coastal system later in the week**

Ensemble guidance, which uses multiple model simulations to assess the range of possible outcomes, remains in good agreement that an unusually strong area of high pressure will develop over Quebec Tuesday and persist into Wednesday and Thursday. This system is likely to keep temperatures across New England cooler than normal, generally in the low to mid 60s, as a cooler air mass settles in and northeasterly winds persist for several days.

Despite the large area covered by the Canadian high pressure system, forecast guidance indicates that a weak low pressure system could develop Tuesday over the Mid-Atlantic region and move far enough north into New Jersey to bring spotty showers to southern New England. There is still uncertainty about how far north this low will move, but there is general agreement on at least a low-end chance of precipitation along the southern coast Tuesday, with higher chances across southern Connecticut and closer to New York City.

Both individual forecast models and ensemble guidance continue to indicate the potential for a coastal low to develop Wednesday into the latter part of the week. There is still considerable uncertainty at this time. The overall trend has been for the low to slowly move north into the waters south of Nantucket, but the forecast models differ on the exact track. The GFS, or Global Forecast System, takes the low farther northeast and closer to Nantucket, while the ECMWF, or European Centre for Medium-Range Weather Forecasts model, tracks it farther northwest and closer to Long Island.

Regardless of the eventual track, this system could bring strong winds, rain, and the potential for coastal erosion and coastal flooding.

**Winds and marine conditions**

The highest confidence at this time is for strong winds, especially over the ocean waters. As the coastal low strengthens and approaches from the south, the Canadian high pressure system over Quebec is also expected to strengthen and expand. This would create an increasingly tight pressure gradient over New England, supporting stronger winds.

There is still uncertainty regarding how strong the low and high pressure systems will become and exactly where the low will track. That means there is still uncertainty about how strong the overall wind field will become. However, confidence is increasing that gale force winds will develop across the southern ocean waters. A Gale Watch has been issued for Tuesday evening through at least Thursday morning.

The latest ensemble guidance also shows roughly a 50 percent probability of storm force wind gusts across the ocean waters south of Long Island and Block Island. There are also 20 to 30 percent probabilities of storm force gusts over Nantucket Sound and Cape Cod Bay as the coastal low strengthens Friday into Saturday.

Winds over land along the south coast, Cape Cod, and the Islands are expected to be somewhat weaker than the marine winds, but still gusty, generally around 25 to 35 mph.