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 180551
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
151 AM EDT Tue Aug 18 2026

.WHAT HAS CHANGED...
Aviation section updated for 06z TAFs.

&&

.KEY MESSAGES...

- Fair and less humid Tuesday with gradual clearing. A high risk
  of rip currents develops across east-facing beaches by Tuesday
  afternoon.

-  No washouts expected, though several opportunities for
   showers return from mid to late week.

&&

.DISCUSSION...
KEY MESSAGE 1...Fair and less humid Tuesday with gradual clearing. A 
high risk of rip currents develops across east-facing beaches by 
Tuesday afternoon. 

Gradual clearing develops from W to E Tuesday as low pressure slowly 
pulls away from the region. Guidance shows areas of low clouds and 
fog lingering for much of the day across coastal areas with the help 
of cyclonic onshore flow. Thus, expecting high temperatures to stay 
in the lower to mid 70s for coastal areas, and perhaps even the 
upper 60s for the outer Cape. It will be quite humid closer to the 
coast with onshore flow advecting moisture inland. Elsewhere, it 
will be drier as the flow turns to the NW through the day. Further 
inland, it looks to be a warmer and drier day with highs in the low 
to mid 80s. Heat index values climb into the upper 80s to near 90 
for a time Tuesday afternoon. For those heading to the beach Tuesday 
afternoon, a Rip Current Statement is in effect for east-facing 
beaches Tuesday. Those heading to the beach should remain aware of 
local conditions and check with lifeguards or beach staff regarding 
rip current risks at their specific location.


KEY MESSAGE 2...No washouts expected, though several opportunities for showers 
return from mid to late week.

Generally zonal flow aloft prevails Wednesday 
while an upper level low tracks well north across the Hudson 
Bay. Conditions are likely to stay dry during the day with 
temperatures in the low to mid 80s. A weak piece of shortwave 
energy shifts in from the west later Wednesday. While the better
forcing remains further north and west, there is a low 
probability for an isolated shower in western MA Wednesday 
night.

Another shortwave in the flow moves through Thursday accompanied by 
better ascent and plume of above normal moisture to support showers. 
There is still some uncertainty across guidance with the track of 
the wave. The ECMWF (ens and deterministic) leans toward a more 
southern track with the higher ensemble probabilities (60-80%) for 
any rain accumulation extending across the south coast to southeast 
MA, and Cape/Islands. The GEFS/GFS has shown a wider footprint of 
showers with similar probabilities across all of southern New 
England. Any amounts are likely to range from a trace to a few 
tenths of an inch.  

We'll be in a post-frontal airmass Friday resulting in slightly 
cooler temperatures in the mid 70s to low 80s and a downtick in 
humidity. The eastern coastal areas will likely end up on the cooler 
end of that temperature range given the easterly onshore flow. High 
pressure builds in from the west bringing dry conditions to most of 
the region. However, there are indications across model guidance of 
a boundary stalling off the east coast with a series of embedded 
shortwaves riding that boundary Friday through the weekend. This may 
bring periodic chances for showers, perhaps some thunderstorms if 
the waves align with diurnal heating. The higher risk for 
showers will the for south coast extending to Cape Cod/Islands.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

Through 12z...Moderate confidence

Pockets of IFR are continuing to develop across the region, 
with some areas reaching LIFR. Notably, coastal terminals have 
hit this sooner. Light E to NE winds continue over more coastal
terminals with calm conditions persisting over the interior 
terminals.

Tuesday...Moderate confidence (ceilings)

MVFR to IFR conditions to start, with improvement to VFR from west 
to east between 17Z and 20Z. Improvements for terminals further
east may be slower and may only top out to MVFR based on
guidance, though VFR by 00z is a possibility for Cape/Islands
terminals. Light N winds become more NW during the afternoon for
the interior terminals, while onshore NE/E winds continues for
eastern terminals, generally at 5-10 kt. Higher winds above 10
kt are possible for ACK.

Tuesday Night...Moderate confidence. 

VFR across the interior, though MVFR towards the Cape/Islands,
along with RI terminals, depending on how thick cloud cover
remains. Otherwise, SCT to FEW at lower ceilings. ACK could see
return of IFR conditions. Light NW to SW winds less than 10 kt
with patchy fog possible.

Wednesday...High confidence.

VFR. WSW winds over much of the region, more SSW over the
coastal areas all at 5-10 kt.

KBOS Terminal...Moderate confidence.

LIFR visby possible periodically early this morning through at
least 08z. Exact timing of improvements to VFR lower 
confidence, but more likely between 16-19Z. SCT MVFR decks 
possible through the afternoon. Winds NE becoming E in the 
afternoon 7-10 kts. 

KBDL Terminal...Moderate confidence.

MVFR conditions have just moved in to the terminal and are
expected to continue through the rest of tonight into the
mornings hours. Periods of IFR cannot be entirely ruled out for
the early morning hours. Chance of fog remains.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: VFR. 

Thursday: VFR. Chance SHRA.

Thursday Night through Friday: VFR. Slight chance SHRA.

Friday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA.

Saturday: VFR. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Tuesday Night...Moderate confidence.

SCA conditions subside Tuesday as low pressure shifts farther 
east. Seas subside to 2 to 4 ft, with light northerly to north- 
northwest winds generally less than 15 kt. High risk of rip
currents for east-facing beaches across E Massachusetts as well
as the Cape and Nantucket.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: Winds less than 25 kt. 

Thursday: Winds less than 25 kt. Slight chance of rain showers.

Thursday Night: Winds less than 25 kt. Chance of rain showers,
slight chance of thunderstorms. 

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Risk for Rip Currents from 8 AM EDT this morning through this 
     evening for MAZ007-015-016-019-022-024.
RI...None.
MARINE...Small Craft Advisory until 2 AM EDT early this morning for 
     ANZ254>256.

&&

$$

DISCUSSION...Mensch/FT
AVIATION...Hrencecin/Mensch/FT
MARINE...FT