Lexington Weather

Lexington, Massachusetts, USA

37°F

1/11/2026 11:31am

Lexington Conditions: Mostly cloudy
Temperature: 37.2°F / 2.9°C
Dew Point: 36.1°F
Relative Humidity: 96%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.65 in Falling Slowly
Visibility: 10 miles
Rain Today: 0.07 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 102319
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
619 PM EST Sat Jan 10 2026

.WHAT HAS CHANGED...
No significant changes needed to the forecast from the previous
update.

&&

.KEY MESSAGES...

- Rain develops late this afternoon for most. Light- 
  accumulating icing in northern and western interior sections 
  of Southern New England, resulting in slippery 
  roads/sidewalks. Precipitation ends by the pre-dawn Sunday 
  hours for most, but rain lingers over Cape and Islands thru 
  Sunday morning.

- Turning windy and much colder Sun night into Mon, with hit- 
  or-miss snow squalls early Sun night and increasing wind gusts
  into the 35- 50 mph range late Sun night into early Mon.

- Dry weather with temperatures returning to above normal levels
  through midweek. Monitoring a potential coastal storm system
  late next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Rain develops late this afternoon for most. Light-
accumulating icing in northern and western interior sections of 
Southern New England, resulting in slippery roads/sidewalks 
overnight. Precipitation ends by the pre-dawn Sunday hours for most, 
but rain lingers over Cape and Islands thru Sunday morning.

A quasi-stationary frontal boundary draped eastward across the mid-
Atlc region is associated with a shield of rain from just south of 
NYC westward through the Alleghany Mtns in PA. This feature returns 
northward as a warm front late this afternoon to early tonight, 
roughly between 4 to 8 PM from the south coastal waters to northern 
MA, spreading its precipitation shield northward. 

Temperatures should remain warm enough for most of Southern New 
England for a period of steady light rain, to at times moderate 
rains in RI and SE MA. Further north and west into the interior 
higher terrain areas (Berkshires, northwest Middlesex and northern 
Worcester Counties), the combination of a cold air damming/drainage 
signature indicated in most model sea level pressure/sfc temp fields 
and initial wet-bulb cooling, temperatures hovering around the 30 to 
32F range support a period of light-accreting freezing rain tonight 
into the overnight hours. Warm nose between 850 mb as much as 6
to +10C advecting in. Following the FRAM methodology, rather 
light winds and light precip rates should help to accrete ice 
readily, although sfc temps are rather borderline and this area 
is more removed from where the heavier QPF will be. Winter 
Weather Advisories remain posted for the east slopes of the 
Berkshires and northern Worcester and northwest Middlesex 
Counties; overall not much change to forecast flat ice 
accumulations of around a tenth to two tenths of an inch, 
resulting in slippery untreated sidewalks and primary/secondary 
roads. Will also mention that due to the presence of a shallow 
layer of sub-freezing air around 925 mb (as low as -2C) below 
the warm nose likely from the initial wet-bulb cooling, areas in
the Merrimack Valley, North Shore and perhaps into the Assabet 
Valley and part of Metrowest could see rain mixed with re-frozen
ice pellets with sfc air temps in the 35-37F range, before 
turning to plain rain. This wouldn't be of any impact though, 
but it wouldn't shock to hear of reports of sleet mixed with 
rain in those locations until the shallow sub-freezing layer 
underneath the warm nose modifies. Temps to be slowly warming to
above-freezing levels by Sun morning.

Although rain lingers along the Cape and Islands into Sun morning, 
the rest of Sun trends dry with slowly modifying temps amid weaker 
cool advection. The real punch of colder air arrives later Sun/Sun 
evening, to be discussed below.

KEY MESSAGE 2...Turning windy and much colder Sun night into Mon, 
with hit-or-miss snow squalls early Sun night and increasing wind 
gusts into the 35-50 mph range late Sun night into early Mon.

Rather potent 500 mb shortwave trough and associated 925 mb 
cold front races through Southern New England late Sunday night,
thinking timing from around 7-9 PM into the Berkshires and 
around 9 PM to midnight toward the eastern MA coast. Even though
temps will be steadily falling, steep lapse rates from sfc to 
nearly 800 mb generate enough shallow instability to support a 
risk for scattered, but brief, passing snow showers and possible
snow squalls with the cold front's passage. Snow Squall 
Parameter values are rather high in the 1-3 unit range largely 
from the steeper lapse rates, although moisture is lacking. For 
context, I don't view this as a higher-end snow squall scenario 
like what happened on the morning of New Years' Day which should
still be somewhat fresh in peoples' minds, but there could be 
some reduced visbys with coatings of snow. 

West-northwest wind gusts then pick up substantially post-cold 
front, with efficient mixing due to the colder air working in 
aloft. BUFKIT profiles still show speeds at top of the mixed 
layer in the 40 to 45-kt range, with gusts developing in most 
areas late Sunday night to around midnight. Peak of the gusts 
take place overnight to early Monday, with speeds in the 35-45 
mph range with occasional gusts around 50 mph around the higher 
terrain. Wouldn't rule out the need for wind advisories for the 
higher terrain but it still looks too borderline for those as 
yet; depending on how much freezing rain develops tonight/early 
Sunday, that is a factor which could tilt a decision towards 
issuing one. Nonetheless, Sunday night turns windy and cold, 
with apparent temps around 5-15 degrees above zero. 

KEY MESSAGE 3...Dry weather with temperatures returning to above 
normal levels through midweek. Monitoring a potential coastal storm 
system late next week. 

Our weather pattern then turns quieter as we move into early 
next week. It looks as though the period of colder air that 
settles in Sunday night into Monday is short-lived. Dry weather,
easing winds and temperatures recovering back toward above 
normal levels (upper 30s to lower-mid 40s) Tue/Wed. 

Will be monitoring developments pertaining to a possible coastal 
storm system around the Thu/Fri timeframe. Weather pattern 
across CONUS becomes amplified late in the week with a deep 
upper level ridge over the Pac NW and a downstream amplified 
trough from eastern Canada southward to the TN Valley/Gulf 
region. Teleconnections have been keying on this late-week 
period as a potentially favorable one for possible coastal 
storm development and is one we'll have our eyes on. While there
are some deterministic solutions which show a more impactful 
storm and some others which are shutouts, ensemble means still 
depict a very broad area of possible development, ranging from 
offshore the Carolinas to as far north as the 40/70 benchmark. 
There is still too much uncertainty in the specific details 
regarding this potential storm's track, location and strength, 
and those details will in part hinge on the position and tilt of
the deep upper trough and if an embedded shortwave in the OH/TN
Valleys can close off early enough to pull any offshore storm 
closer to the coast. Because of the uncertainty I didn't make 
many changes to NBM at this point, and will let more coherent 
trends in the guidance dictate adjustments. Still, this is a 
period we're going to need to keep close watch of.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

TAF Update: 00z

Tonight... High confidence in trends, moderate confidence in
timing.

Moderate to heavy rain will help saturate the low levels 
between 02-04z tonight, allowing CIGS to turn IFR/LIFR. CIGS 
remain IFR/LIFR overnight after the rain ends due to light ENE 
flow. Rain ends between 06-08z tonight with showers lingering 
into Sunday morning. Significant LLWS concerns for the Cape and 
Islands tonight as 2kft winds approach 60 to 70 knots from the 
SW while a steep low level inversion could keep surface winds 
under 20 knots from the SE.

Sunday... High confidence in trends, moderate confidence in
timing.

Winds turn WNW Sunday morning, but CIGS may be slow to improve
until Sunday afternoon when drier low level air begins to work
in behind the low. Rain showers and low CIGS will linger for 
the Cape and the Islands for much of the day.


KBOS Terminal... Moderate Confidence. 

VFR with winds shifting east this afternoon. Rain will reach the
terminal between 23-00z, however IFR/LIFR CIGS will lag behind
the rain due to low level dry air. Moderate rain should reach
the terminal around 03z along with the IFR/LIFR CIGS. CIGS
remain IFR/LIFR through mid Sunday morning with lingering
showers and drizzle. Only moderate confidence on when CIGS
improve on Sunday. Current expectation is CIGS wont improve until
late Sunday morning to early afternoon.

KBDL Terminal... Moderate Confidence.

VFR with light and variable winds this afternoon. Rain moves in
between 21-22z this evening. IFR CIGS will lag behind the rain 
until closer to 02z when moderate rain move in. Rain ends 
between 06-07z, however showers could linger until day break. 
CIGS improve to MVFR/VFR mid to late Sunday morning.

Outlook /Sunday Night through Thursday/...

Monday: VFR. Strong winds with local gusts up to 40 kt. 

Monday Night through Tuesday Night: VFR. Breezy. 

Wednesday: Mainly VFR, with local IFR possible. Breezy. Slight
chance RA.

Wednesday Night: Mainly VFR, with local MVFR possible. Chance
RA, chance SN.

Thursday: VFR. Slight chance RA, slight chance SN.

&&

.MARINE...
Forecaster Confidence Levels...

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

Tonight through Sunday night: High confidence.

A stationary frontal boundary will bring a rain to the coastal 
waters this afternoon through much of Sunday. Winds tonight will be 
out of the ESE at 10-20 knots with gusts up to 30 knots possible in 
the southern waters. Seas increase to 4-7 feet.  Winds turn West on 
Sunday and increase to 30-40 knots by Sunday evening. Gale watch has 
be converted to a gale warning for Sunday night into Monday morning. 
Seas increase to 7-10 feet Sunday night.

Outlook /Sunday Night through Thursday/...

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

Monday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft. 

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

Tuesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Local rough seas. 

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

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

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Weather Advisory until 10 AM EST Sunday for MAZ002-004-
     008-009-026.
RI...None.
MARINE...Gale Warning from 7 PM Sunday to 7 AM EST Monday for 
     ANZ230>237-251.
     Gale Warning from 7 PM Sunday to 10 AM EST Monday for ANZ250-
     254>256.

&&

$$

DISCUSSION...Loconto
AVIATION...Loconto/Dooley/KP
MARINE...Loconto/KP