AFD - Boston

Updated: 126 PM EST Tue Dec 9 2025

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Synopsis

A moisture starved shortwave crosses the region tonight with a period of mainly scattered light snow showers. A more significant disturbance brings much milder temperatures and a period of mainly rain Wednesday afternoon and evening with any snow confined to the highest terrain of the Berkshires and northern Worcester Hills. A cold front crosses the region later Wednesday night...bringing mainly dry, but blustery and cold weather returning Thursday into Friday. Low pressure may bring snow with even some ice/rain to the region Saturday night into Sunday depending on its track. This will be followed by another shot of arctic air and well below normal temperatures early next week.

Forecast & Tides
Tue
35° 26°
Wed
48° 30°
Thu
38° 22°
Fri
35° 25°
Sat
39° 27°
Sun
36° 15°
Mon
27° None°
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Near Term

THROUGH TONIGHT
Key Messages...

* Cold/dry conditions persist for the rest of the afternoon

* Southerly winds support increasing temperatures overnight

* Slight chance for some snow showers mainly across eastern MA

Rest of Today and Tonight

High pressure continues to support sunny skies, light winds, and dry weather for the rest of the afternoon. As high pressure shifts east overnight, return flow from the south will support increasing temperatures through day break. Thus, we can actually expect the overnight low to occur around midnight. A moisture starved short-wave disturbance aloft moves overhead after midnight. This may support a few widely scattered snow showers, mainly across eastern MA. Not expecting any significant impacts or accumulations with only a dusting at locations where snow showers develop.

Temperatures rise to the mid to upper 20s across most of interior southern New England by sunrise. Low 20s for northwest MA/high elevations and upper 30s to low 40s for Cape/Islands..

Short Term

WEDNESDAY THROUGH WEDNESDAY NIGHT
Key Messages...

* Increasing cloudiness tomorrow with more mild temperatures during the day

* Rain/snow Showers overspread the region from west to east tomorrow afternoon and evening

* Cold front clears clouds/showers out overnight and is followed by cold/blustery conditions

Wednesday and Wednesday Night

Warm advection and strong southerly winds support increasing temperatures tomorrow with 925 and 850 hPa temps rising to near 0C by the afternoon. This will support mild surface temperatures in the upper 40s to low 50s across southeastern MA and RI tomorrow. Areas across western MA and CT will be much cooler in the upper 30s to low 40s. Rain/snow showers begin to overspread the region from west to east tomorrow afternoon into tomorrow evening.

Mainly expecting rain with some snow showers possible at the higher elevations of The Berkshires and northern Worcester Hills. Accumulations will be minor, but may approach 1-2 inches on the east slopes of The Berks. Elsewhere, mainly in Worcester County, only expecting a dusting if any accumulation at all.

A cold front moves over the region tomorrow night and clears skies from west to east after midnight. This will be followed by a brisk west/northwest wind and temperatures dipping back down into the upper 20s/low 30s by Thursday morning..

Long Term

THURSDAY THROUGH MONDAY

Key Messages:

* Falling temps Thurs with very cold and windy conditions Thurs aftn to evening.

* Dry with modifying temps starting Fri into early Sat.

* Still monitoring low pressure which may bring accumulating snow and/or a wintry mix of precip types to Southern New England Sat night or into Sun, but the storm's track and strength are both uncertain.

* Another shot of modified-Arctic air and blustery winds for early next week.

Details:

Thursday:

Closed 500 mb low and its associated reservoir of modified-Arctic air will entrench itself into Southern New England on Thurs. Tightening NWly pressure gradient combined with a deepening mixed layer supporting enhanced NW wind gusts will make for a windy and very cold day.

Wind gusts at top of the mixed layer are progged around 45 to 50 kt, and efficient mixing should allow for gusts to near-Advisory levels (35 to 45 mph). The bigger impact though is that it will lead to falling temperatures and biting wind chills through the afternoon; expect mid-morning highs then temps fall though the teens to mid 20s by early evening. By early evening, wind chills run in the single digits above zero in the terrain to the mid/upper teens above zero for the remainder of Southern New England, including the Cape and Islands. Because the NW winds stay up for the entire evening under a continued tight NW pressure gradient, nighttime lows may only fall into the teens above zero, but wind chills in the 5 above to 5 to 10 below zero range by sunrise Fri.



Friday:

Frigid start, although we enter into a warm advection pattern starting Fri; while temps are still below normal, easing winds will help take the edge off the wind chill. Full sun should allow highs in the 20s to around freezing in/around the terrain and in the low to mid 30s for lower elevations and the coasts. Dry weather for the evening despite a modest increase in clouds, so some radiational cooling likely to be offset by the warmer profiles (925 mb temps warming to around -4 to -6C) and the cloud cover for lows in the mid teens to lower to mid 20s.

The Weekend:

Increasing cloud cover on Sat but generally dry during the daytime hours aside from a spot, non-impactful snow shower underneath the cloud cover, with highs in the 30s, to near 40 along the south coast.



Still monitoring developments regarding a potential storm system that could threaten Southern New England later Sat night and/or Sunday, as active northern stream energy pattern continues to favor Clipper type systems. Besides the usual timing and storm track uncertainties at this time range, global models still show a disparity of potential outcomes due to differences in phasing between a closed low over central Canadian Prairies and a weak vort max coming around the northern Rockies/central Plains/upper Midwest. These outcomes range from not much at all as phasing between the two streams occurs too late/offshore (e.g. GFS/its ensemble) to stronger/earlier phasing between the two energy streams (e.g. ECMWF/Canadian camp) leading to a more robust low pressure which treks somewhere ranging from interior northern New England and/or as far south as the CT-RI-MA I-95 corridor.

Depending on the exact track...the international model solutions could favor an accumulating snow for parts of or much of Southern New England Sunday, with better chance for interior Southern New England, although a more interior storm track would introduce more wintry mix (PL/FZRA) or rain into the mix. Thus as mentioned, quite a few uncertainties that still need to be ironed out, but these are details we'll be keeping tabs on as we move through the workweek and it is too early to lock into any one outcome as yet.

Monday and Tuesday:

System exits early on Monday which brings decreased cloudiness, but with it comes another dump of colder, modified-Arctic air and blustery conditions. .

Aviation

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

18Z TAF Update...

Through 00Z... High Confidence

VFR. Light southwest winds

Tonight...High Confidence

Mainly VFR with some MVFR cloud bases right around 3000 feet possible. Low chance for some snow showers between roughly 03-07Z as a weak disturbance moves over the region. Winds becoming more steady out of the southwest with speeds increasing to around 10 knots with some 20 knot gusts possible over The Cape/Islands.

Tomorrow... High Confidence in trends, moderate in timing

VFR likely through 18Z, then MVFR ceilings overspread the region from west to east with -RA. Not expecting MVFR ceilings to reach BOS/PVD until 20-22Z time frame. Cape/Islands terminals don't fall below VFR until after 00Z.

Tomorrow Night... High Confidence

MVFR ceilings reach Cape/Islands between 00-06Z. Conditions gradually improve back to VFR between 06-12Z as a cold front sweeps across the region. Winds shift to the west/northwest behind the front with sustained winds around 15 knots.

KBOS Terminal...Moderate Confidence in TAF.

Low chance for -SN overnight between roughly 03-09Z.

KBDL Terminal...High Confidence in TAF.

Outlook /Thursday through Saturday/...

Wednesday Night: Mainly VFR, with local IFR possible. Windy with areas of gusts up to 35 kt. Chance RA, slight chance FZRA, patchy BR.

Thursday through Thursday Night: VFR. Windy with gusts up to 35 kt.

Friday: VFR. Windy with local gusts up to 30 kt.

Friday Night through Saturday: VFR. Breezy. Slight chance SN.

Marine

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

Tonight through Wednesday night...High confidence.

Gale Watch upgraded to gale warning for tonight and tomorrow as a LLJ allows for SW wind gusts of 35 knots to develop over the coastal waters. Showers move over the coastal waters tomorrow evening and tomorrow night. Gale force winds mainly from the southwest through Thursday morning.

Outlook /Thursday through Saturday/...

Wednesday Night: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 12 ft. Chance of rain, patchy fog.

Thursday: Moderate risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Slight chance of rain.

Thursday Night: Moderate risk for gale force winds with gusts up to 40 kt. Areas of rough seas. Slight chance of snow.

Friday: Strong winds with gusts up to 35 kt. Areas of rough seas.

Friday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Slight chance of rain.

Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Chance of rain, slight chance of snow.

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