Lexington Weather

Lexington, Massachusetts, USA

84°F

5/27/2026 3:52pm

Lexington Conditions: Partly cloudy
Temperature: 83.8°F / 28.8°C
Dew Point: 61.5°F
Feels Like: 84.4°F
Relative Humidity: 47%
Wind: S 1 mph, 10-min avg: Calm, gust: 2 mph
Barometer: 29.62 in Falling Slowly
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 202306
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
706 PM EDT Wed May 20 2026

.WHAT HAS CHANGED...
The risk for severe weather has diminished somewhat with best
chance near the south coast.

&&

.KEY MESSAGES...

- Scattered showers and thunderstorms developing through early
  evening with main focus across CT, RI and SE MA, especially 
  near the south coast. A few strong to severe storms possible. 

- Another round of scattered showers later tonight into Thu
  morning for CT, RI and SE MA. Much cooler Thu then dry and 
  seasonably mild Fri.

- Cooler temperatures through Memorial Day Weekend. Unsettled 
  weather returns for the weekend with periods of rain possible,
  but confidence is low.

&&

.DISCUSSION...
KEY MESSAGE 1...Scattered showers and thunderstorms developing 
through early evening with main focus across CT, RI and SE MA, 
especially near the south coast. A few strong to severe storms 
possible. 

Cold front has pushed southward into northern MA with wind 
shift to W-NW. Winds have veered to the W ahead of the front 
which will limit low level convergence somewhat. As front moves 
south and approaches south coast, expect scattered showers and 
t-storms to develop. This is where best instability, up to 1000 
J/kg of MLCAPE, is located along with best convergence as winds
are more SW near the coast. Effective shear is marginal, up to 
25 kt which is a bit lower than you want to see for storm 
organization. However, steep low level lapse rates and inverted 
V soundings support localized strong to damaging wind gusts with
any stronger storms that develop. The best chance for a few 
strong to severe storms are near the south coast from 5-8 pm, 
with HREF max updraft field targeting southern RI. However, 
severe threat is greatest to the SW. 

KEY MESSAGE 2...Another round of scattered showers late tonight
into Thu morning for CT, RI and SE MA. Much cooler Thu then dry
and seasonably mild Fri.

The cold front moves south of New Eng tonight. A weak wave is 
forecast to develop along the boundary as shortwave energy 
approaches from the west toward Thu morning. Northern edge of 
higher PWATs and deep moisture plume lingers near the south 
coast where scattered showers may redevelop late tonight and 
linger into Thu morning, with best chance along and south of 
HFDL-PVD-PYM. Otherwise, drier air will be pushing south from 
northern New Eng leading to partly sunny skies developing 
across northern MA during the afternoon. Much cooler day Thu as 
925 mb temps drop to 7-9C leading to highs in the 60s. 

The shortwave moves east of New Eng by late Thu followed by 
subsidence then upper ridge builds over the Gt Lakes with dry 
NW flow across New Eng through Fri. The drier air will reach 
the south coast Thu night with clearing skies. Good radiational
cooling will result in a rather chilly night with lows ranging
from the upper 30s to mid 40s. Sunshine and seasonably mild 
temps Fri as high pres builds into the region. Highs will reach 
the upper 60s and lower 70s but cooler along the coast where 
sea-breezes are expected to develop. 

KEY MESSAGE 3...Cooler temperatures through Memorial Day 
Weekend. Unsettled weather returns for the weekend with periods
of rain possible, but confidence is low. 

High pressure and mid-level ridging overhead for Friday 
bringing dry conditions and seasonal temperatures. Expect high 
temperatures in the upper 60s/low 70s for most inland areas 
while easterly flow will keep the east-facing coastline cooler 
in the 60s. 

For the holiday weekend, we continue to see a signal for a 
potentially unsettled weather pattern with a period or two of 
showers. However, there continues to be a notable spread among 
deterministic and ensemble guidance on the track and timing of 
disturbances associated with a larger system moving through the
Ohio Valley. While the ECMWF and some runs of the GFS show rain
chances later Saturday into Sunday, their AI-renditions have 
been dry for Saturday. Beyond that point, differences even 
emerge between the AI guidance on the timing of rain sometime 
Sun or Mon. This spread in solutions has lead to a bullish view 
when assessing the ensemble guidance for rain probabilities over
the weekend. Ensembles have blanketed southern New England with
moderate probabilities for at least 0.01" of rain later Sat 
into Sun and Monday. Given the notable spread in guidance, rain 
chances are still low confidence for the holiday weekend. 
Leaning toward a wetter weekend based on range of ensemble 
guidance leaning in that direction. On the positive side, if 
Saturday ends up wetter, there is some agreement with the 
showers coming in later Saturday which at least keeps part of 
that day potentially dry! Given that guidance is leaning more 
unsettled, temperatures this weekend will be cooler in the 50s 
and low 60s. There is a signal for temperatures to trend warmer 
into early next week.

&&

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

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

00Z TAF Update... 

Tonight...Moderate confidence.

Mainly VFR cigs, but showers and scattered t-storms will impact
the south coast 00-04z with brief downpours and lower cigs/vsbys
possible. Gusty W-NW wind diminishing and becoming N overnight. 

Thursday...High confidence.

Mainly VFR cigs. Scattered showers redeveloping near the south 
coast Thu morning with brief MVFR possible. N wind 5-10 kt with
sea-breezes developing by midday.

Thursday night...High confidence.

VFR. Light wind. 

KBOS...High confidence in TAF.

KBDL...High confidence in TAF.

Outlook /Friday through Monday/...

Friday through Friday Night: VFR. 

Saturday: VFR. Chance SHRA.

Saturday Night through Sunday: VFR. Breezy. SHRA likely.

Sunday Night: VFR. Chance SHRA.

Memorial Day: Mainly VFR, with local MVFR possible. Chance
SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Wednesday Night: High confidence. 

SW gusts to 25 kt over nearshore waters will diminish this
evening with seas gradually subsiding tonight. Winds will shift
to NW this evening then N overnight. NE wind Thu morning with 
sea-breezes developing over nearshore waters in the afternoon.
Light winds Thu night becoming N-NE overnight. 

Outlook /Friday through Monday/...

Friday through Friday Night: Winds less than 25 kt. 

Saturday: Winds less than 25 kt. Chance of rain showers. 

Saturday Night through Sunday: Low risk for Small Craft
Advisory winds with gusts up to 25 kt. Local rough seas. Rain
showers likely. 

Sunday Night: Winds less than 25 kt. Seas up to 5 ft. Rain
showers likely. 

Memorial Day: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain showers.

&&

.CLIMATE...
Record Highs for Wed May 20...

BOS 91/1996
BDL 99/1996
PVD 95/1996
ORH 91/1903

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ230-
     232>235-237.
     Small Craft Advisory until 2 AM EDT Thursday for ANZ254>256.

&&

$$

DISCUSSION...KJC/Mensch
AVIATION...KJC
MARINE...KJC
CLIMATE...BW