Lexington Weather

Lexington, Massachusetts, USA

66°F

8/24/2026 6:41am

Lexington Conditions: Mist, Overcast
Temperature: 65.8°F / 18.8°C
Dew Point: 64.6°F
Relative Humidity: 96%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.85 in Steady
Visibility: 2 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 190540
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
140 AM EDT Wed Aug 19 2026

.WHAT HAS CHANGED...
Small lowering of shower/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 resulting in rip
currents along primarily east facing beaches today. This energy 
will slowly be diminishing this evening and overnight. As that 
happens, the risk for rip currents along primarily east facing 
beaches will also slowly 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's taken awhile, much of the low clouds across the
eastern half of southern New England have finally started to
lift and break up. Satellite imagery shows daytime cumulus
developing across the interior thanks to relatively abundant low
level moisture. However the latest mesoanalysis does not show
much mixed layer CAPE and still some CIN due to a weak inversion
aloft. Although a shower or isolated brief thundershower is
possible, the chances are pretty low. Did maintain continuity
with previous forecasts and painted in a roughly 20% chance,
mainly across the Worcester Hills into NE CT and northern RI.
This is where the thermal gradient (due to slightly cooler
temperatures where the low clouds hung around longest and where
more sunshine has developed) will also be maximized. Otherwise,
the next 36 hours will be dry for the vast majority of the
region. Could be another round of low clouds and some fog across
southeast MA/Cape/Islands late tonight due to the still somewhat
humid airmass. Otherwise models are all consistent with dry
weather tomorrow. With plenty of sun and 925mb temperatures
around 20C, we should see surface temperatures either side of
30C (ie: mid 80s F). Stuck with model blend for that reason.
Quiet and seasonable conditions continue Wednesday night. 


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

Guidance continues to show a shortwave moving east towards the CWA 
on zonal flow Thursday. Aloft, the jet stream becomes cyclonically 
curved placing our region under the jet's left exit region. These 
mid and upper level dynamics provide ample forcing for 
precipitation. The caveat here will be dry low and mid level 
moisture profiles across much of the region. Thus, expecting mainly 
light showers across the southern portion of the CWA with mostly 
cloudy skies elsewhere. Still, there are some discrepancies within 
guidance suites. Namely, the global models, including the NBM, show 
a drier solution with probs of QPF exceeding 0.25" less than 30%. In 
contrast, CAMs show a more amplified, moisture-rich wave with 
locally heavy rain and a low risk for thunderstorms. Think the 
solution lies somewhere in between the two extremes with scattered 
showers possible mainly along and S of the Mass Pike Thursday 
afternoon and evening. 

The frontal wave passes E of the region late Thursday. Dew point 
temperatures crash into the upper 50s Friday as high pressure builds 
overhead. Temperatures will likely be in the low 80s and down to the 
mid 70s, particularly along the coasts where onshore winds will keep 
it slightly cooler. 


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

Guidance shows an even larger shortwave arriving from the Great 
Lakes later Saturday with plenty of upper-level energy. Behind the 
lead shortwave, a series of shortwaves moving along the boundary 
that may stall just off the east coast could bring chances for 
showers. Thunderstorms could be a possibility depending on if these 
waves could take advantage of daytime heat. More details will become 
apparent as we approach this timeframe. At the moment, guidance 
blends show a 30-50% chance of rain through much of the interior and 
60-70% along the coast from Saturday night to Monday morning.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

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

06z TAF Update

Through 12z...Moderate confidence.

MVFR for most with some areas of IFR. Some patchy fog remains
possible between 08z-11z. Light to calm winds through the rest
of tonight before more SW winds pick up after sunrise.

Today...High confidence.

MVFR to start, becoming VFR within a few hours after sunrise. SW
winds between 5-10 kt, with gusts to just under 20 kt a
possibility for the Cape and Island terminals. Seabreezes not
expected given the strength of SW flow and forecast soundings
indicating good diurnal mixing, though some models do continue
to hint at it for BOS.

Tonight...High confidence.

VFR, with the exception of possibly the Cape and Islands, far 
SE MA, and coastal RI. Winds remaining light SW below 10 kt with
calm winds possible over the interior.

Thursday...Moderate confidence.

VFR with chances for SHRA. TSRA not expected. 

KBOS Terminal...Moderate confidence in TAF. Low chance for a
seabreeze in the 16-21z timeframe. Only a few models indicate it
and keep it short-lived, so opted to hint at it with a S wind at
17z. Would not be surprised if this does not happen though,
given the strong SW flow over the region.

KBDL Terminal...High confidence in TAF.

Outlook /Thursday through Sunday/...

Thursday: VFR. Slight chance SHRA.

Thursday Night through Friday Night: VFR. 

Saturday: VFR. Chance SHRA.

Saturday Night: Mainly VFR, with local IFR possible. Chance
SHRA.

Sunday: Mainly VFR, with local IFR possible. Chance SHRA,
slight chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Thursday...High confidence.

Generally light winds into Thursday with only weak pressure
patterns. Seas will continue to diminish as the swell energy
slowly diminishes. 

Outlook /Thursday through Sunday/...

Thursday: Winds less than 25 kt. 

Thursday Night through Friday Night: Winds less than 25 kt.
Chance of rain showers. 

Saturday through Saturday Night: Winds less than 25 kt. Rain
showers likely, slight chance of thunderstorms. 

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

DISCUSSION...FT/Nash
AVIATION...Hrencecin
MARINE...FT/Nash