Lexington Weather

Lexington, Massachusetts, USA

31°F

12/14/2025 8:51am

Lexington Conditions: Light snow, Mist, Overcast
Temperature: 30.7°F / -0.7°C
Dew Point: 27.9°F
Relative Humidity: 89%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.89 in Rising Slowly
Visibility: ¾ mile
Snow Today: 0.3 in

Southeast Middlesex County, MA - Special Weather Statement
- SEE ALL NEARBY ALERTS -

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 131928
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
228 PM EST Sat Dec 13 2025

.SYNOPSIS...
A fast-moving low pressure will bring accumulating snow
overnight into Sunday morning, especially south of the Mass 
Pike. Ocean effect snow showers will linger into Sunday
afternoon towards the Cape and Islands. A brief shot of arctic
air follows Sunday night into Monday, with wind chill values
dropping to between 0 to 10 below zero. It remains cold Tuesday, 
but a pattern change with a significant warming trend is likely 
Wednesday into Thursday. The milder conditions will likely be 
accompanied by a period of gusty winds and showers sometime in 
the late Thursday into Friday time frame.

&&

.NEAR TERM /THROUGH SUNDAY/...
Key Messages...

* Accumulating snow very late tonight-Sun morning, especially
  south of I-90. Highest accumulations near the south coast.

* Advisory level snowfall expected across much of southeast MA
  and southern RI.

The latest guidance suite continued to narrow the focus on some
of the critical details for this portion of the forecast. That 
said, some uncertainty remains. For example, at what temperature 
does the snow start accumulating on untreated paved surfaces?
Even a 1F degree change could expand the accumulating snow 
window by a few hours. That could make a big difference in 
impacts across our region.

The main concern is with the majority of the snowfall occurring
at night, accumulations are a little more likely to occur than
at the same temperature during the daytime. Some of the higher
resolution guidance with his last suite exhibited a notable
uptick in banding within the dendritic growth zone. Have some
confidence the heaviest snowfall will be towards the south coast
of MA and RI, but still do not know with certainty exactly where
the heaviest band will finally set up. 

Based on this subtle shift farther north and slightly better
dynamics, the Winter Weather Advisory was expanded into northern
Bristol as well as Eastern and Northern Plymouth Counties in MA.
Still kept the goal posts wide with respect to the timing.
Thinking that most areas away from the Cape and islands will
likely be able to have the advisory cancelled earlier than the
7 PM timing.

Steadiest snow will quickly end from west to east through mid 
morning Sunday. Expecting ocean effect snow showers to linger 
across the outer Cape Sunday afternoon and night as arctic air 
pours into our region on NNW-NW flow. Ocean induced CAPE values 
expected to increase to 500-600 J/kg. An additional 1-2" is 
possible on the outer Cape, but boundary layer temperature 
profiles may be a bit warm for additional accumulations during 
the afternoon. 

&&

.SHORT TERM /SUNDAY NIGHT/...
Key Messages...

* Very cold with wind chill values near or below zero

The coldest airmass of the season thus far will move in behind
the snow for Monday night as 850mb temps crash into the -15C to 
-20C range. This will result in overnight low temperatures 
bottoming out in the single digits across the interior, to the 
low teens near the coastal plain. A strong pressure gradient 
will result in gusty winds overnight, around 20-30mph. This will
bring the windchill index/feels-like temperatures down to the 
0F to -5F range, with -5F to -15F in the high terrain. Cold 
weather advisories may be needed in the northern Berkshires for 
Monday morning. 

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Key Messages...

* Remaining Cold Monday and Tuesday. Light snow showers are 
   possible Monday night

* Rapid warming trend Wednesday through Friday

* Late week system looks to bring rain and gusty winds to the  
  region.

The Arctic air mass remains in place through Tuesday as GFS and 
Euro ensembles keep temperature anomalies near 10 degrees colder 
than normal. While it wont be as cold as Monday morning, high
temps will remain in the 20s for Monday, and struggle to top
freezing on Tuesday. Tuesday morning lows drop into the teens
across the region, but with calm winds, the wind chill index
also remains in the teens. A weak shortwave passes through the
region Monday night and could bring some light snow showers to 
the region. With a lack of strong forcing and marginal moisture,
QPF will be light, on the order of a trace to 0.05 inches. Any 
snow that falls will also be light, under a half inch.

An upper-level ridge originating from milder maritime air over
the Pacific Ocean will reach the region by Wednesday, with
850 mb temps rising to +2C. Surface high temps on Wednesday 
jump into the low to mid 40s, with upper 40s to low 50s possible
for Thursday and Friday. Guidance has been relatively consistent 
in showing a strong shortwave trough dropping out of the Great
Lakes on Friday. Temps by Friday will be warm enough to keep
precipitation as all rain. Given the strong WAA, there could be 
some gusty winds associated with this system on Friday, but it 
is far too early to speculate on potential wind impacts at this 
time.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

Tonight and Sunday...Moderate confidence.

VFR conditions dominate during the first half of this evening. 
MVFR-IFR conditions in light snow arrives in the 14/03z to 14/07z
time frame. Expecting mainly snow, but a few hours of rain or 
mixed rain/snow are possible near the Cape and Islands. 
Steadiest snow south of I-90, and especially towards the south 
coast where brief LIFR conditions are possible in snow. Snow 
winds down between 14/12z and 14/16z from northwest to
southeast, but lingers into the afternoon towards the southeast
New England coast. Otherwise, improvement to VFR conditions
expected. Light SW winds tonight shift to the NW at 5 to 10 kt
Sunday. Could become gusty towards the Sunday evening push.

Sunday night...High Confidence.

VFR outside the the outer-Cape/Nantucket where ocean effect snow 
showers may persist Sunday evening. This activity should
dissipate though after midnight. Otherwise, NW wind gusts of 20 
to 25 knots with a few gusts near 30 knots across the high 
terrain and near the coast develop Sunday night.

KBOS Terminal...High confidence in trends. Moderate confidence
in timing. Snow likely develops after 06z, with the bulk of it 
ending before lunchtime Sunday. Total snow accumulations of 1-2"
possible.

KBDL Terminal...Moderate confidence in TAF. Snow develops after
14/03z and ends by mid-late Sunday morning. Total snow
accumulations of 1-3" possible. 

Outlook /Monday through Thursday/... 

Monday: VFR. Breezy. 

Monday Night: VFR. Breezy. Slight chance SN.

Tuesday: VFR. 

Tuesday Night: VFR. Breezy. 

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

Wednesday Night: VFR. Breezy. 

Thursday: VFR. Breezy. Slight chance RA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Sunday Night...High confidence.

Gusty SW winds into this evening ahead of an approaching cold 
front. Widespread rain/snow moves across the waters late tonight
and Sunday morning. Gale Watch Sunday night into Monday as
colder air moving over the waters will result in excellent
mixing conditions. Areas of very light freezing spray likely 
Sunday night. 

Outlook /Monday through Thursday/...

Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Areas of rough seas. Areas of freezing spray
likely.

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

Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. 

Tuesday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Seas locally approaching 5 ft. 

Wednesday: Strong winds with gusts up to 30 kt. Areas of rough
seas. 

Wednesday Night: Winds less than 25 kt. Local rough seas. 

Thursday: Winds less than 25 kt. Areas of seas approaching
5 ft. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Weather Advisory from 10 PM this evening to 7 PM EST 
     Sunday for MAZ017>024.
RI...Winter Weather Advisory from 10 PM this evening to 7 PM EST 
     Sunday for RIZ003>008.
MARINE...Small Craft Advisory until 1 AM EST Sunday for ANZ231>235-237-
     250-251-254>256.
     Gale Watch from Sunday evening through Monday afternoon for 
     ANZ231>235-237-250-251-254>256.

&&

$$

SYNOPSIS...Belk/KP
NEAR TERM...Belk
SHORT TERM...KP
LONG TERM...KP
AVIATION...Belk/KP
MARINE...Belk/KP