Weather for New England and the Northeast

Area Forecast Discussion, National Weather Service Boston/Norton MA 158 PM EDT
Tue Aug 18 2026

**WHAT HAS CHANGED**

A small lowering of shower and thunderstorm chances for Thursday.

**KEY MESSAGES**

* Rip current risk continues along the east coastal areas into this evening.
* Small chance of a shower or thunderstorm through this evening across the interior, otherwise tranquil weather through Wednesday night.
* Unsettled weather returns Thursday with high pressure and pleasant weather following for Friday.
* Another round of unsettled weather possible for the second half of the weekend.

**DISCUSSION**

**KEY MESSAGE 1, Rip current risk continues along the east coastal areas into this evening**

Swell energy coming in from the east has been producing rip currents, mainly along east facing beaches today. This wave energy will slowly diminish this evening and overnight. As it decreases, the rip current risk along east facing beaches should also gradually diminish.

**KEY MESSAGE 2, Small chance of a shower or thunderstorm through this evening across the interior, otherwise tranquil weather through Wednesday night**

Although it took awhile, much of the low cloud cover across the eastern half of southern New England has finally started to lift and break apart. Satellite imagery shows daytime cumulus clouds developing across the interior because of relatively abundant low level moisture.

However, the latest atmospheric analysis shows limited mixed layer CAPE, which is Convective Available Potential Energy, meaning there is not much fuel available for thunderstorms. There is also some CIN, or Convective Inhibition, from a weak layer of warmer air aloft that is limiting rising air.

A shower or isolated brief thunderstorm is possible, but the chances remain quite low. The forecast continues to show roughly a 20% chance, mainly across the Worcester Hills into northeast Connecticut and northern Rhode Island. This area has the strongest temperature contrast because some locations stayed cooler under the low clouds while others received more sunshine.

Otherwise, the next 36 hours should be dry for most of the region. Another round of low clouds and some fog could develop across southeastern Massachusetts, the Cape and the Islands late tonight because of the still somewhat humid air mass. Forecast models remain consistent with dry weather Wednesday.

With plenty of sunshine and temperatures around 68 degrees at the 925 mb level, or roughly 2,500 to 3,000 feet above sea level, surface temperatures should reach the mid 80s. Quiet and seasonable conditions continue Wednesday night.

**KEY MESSAGE 3, Unsettled weather returns Thursday with high pressure and pleasant weather following for Friday**

Forecast guidance continues to show a shortwave, which is a smaller disturbance in the upper atmosphere, moving east toward the region Thursday. The jet stream will become curved in a way that places southern New England beneath the left exit region of the jet. This area can provide additional upward motion and help generate precipitation.

The main limiting factor will be relatively dry air in the lower and middle levels of the atmosphere across much of the region. Because of this, mainly light showers are expected across southern portions of the forecast area, with mostly cloudy skies elsewhere.

There are still some differences among the forecast models. The global models, including the NBM, or National Blend of Models, show a drier solution, with less than a 30% chance of precipitation exceeding 0.25 inches. In contrast, the CAMs, or convection allowing models, show a stronger and more moisture-rich disturbance that could produce locally heavy rain and a low risk of thunderstorms.

The most likely outcome appears to be somewhere between these two extremes, with scattered showers possible mainly along and south of the Massachusetts Turnpike Thursday afternoon and evening.

The frontal disturbance moves east of the region late Thursday. Dew point temperatures will fall into the upper 50s Friday as high pressure builds overhead. Temperatures should reach the low 80s, with readings falling into the mid 70s, particularly along the coast where onshore winds will keep conditions slightly cooler.

**KEY MESSAGE 4, Another round of unsettled weather possible for the second half of the weekend**

Forecast guidance shows a larger upper-level disturbance arriving from the Great Lakes later Saturday, bringing additional energy in the upper atmosphere. Behind the initial disturbance, a series of smaller disturbances could move along a boundary that may stall just offshore.

These disturbances could bring additional chances for showers. Thunderstorms are also possible depending on whether the disturbances can take advantage of daytime heating. More details should become clearer as we get closer to the weekend.

For now, forecast guidance indicates a 30 to 50% chance of rain across much of the interior and a 60 to 70% chance along the coast from Saturday night through Monday morning.