Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Clear
Temperature: 35.1°F / 1.7°C
Dew Point: 32.4°F
Relative Humidity: 90%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.00 in Falling Slowly
Visibility: 10 miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Lexington, MA

        
000
FXUS61 KBOX 092329
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
729 PM EDT Sun Aug 9 2026

.WHAT HAS CHANGED...
Forecast remains on track.

&&

.KEY MESSAGES...

- Humidity briefly trends down tonight, but then rises again
  Monday afternoon. Above normal temperatures continue through
  Tuesday.

- Warmer and less humid Wednesday, with a strong cold front
  moving in early on Thursday bringing a risk for showers and 
  a low risk for storms.

- Nice stretch of later-summer weather Friday into the weekend.

&&

.DISCUSSION...
KEY MESSAGE 1...Humidity briefly trends down tonight, but then rises 
again Monday afternoon. Above normal temperatures continue through 
Tuesday.

Expecting mainly rain-free conditions for this portion of the 
forecast. The exception should be Monday afternoon into the evening, 
when a round of diurnal showers and thunderstorms will be possible.

Humidity drops later tonight behind a weak cold front. This front 
should not go far, and return as a warm front Monday afternoon into 
the evening. Dew points increase again just to the south of this
front. A passing cold pool across northern New England should
help to generate CAPE values of 750-1,250 J/kg by late Monday
afternoon. The greatest risk for any thunderstorms likely
remains west of our region.

Once again, this warm front moves back south as a cold front
Monday night into Tuesday. Not looking humid enough to keep a
mention of showers in the forecast, especially that early in 
the day when this front should pass by. Humidity starts to fall
once more Monday night, but really get into the comfortable
range Tuesday afternoon and night.

KEY MESSAGE 2...Warmer and less humid Wednesday, with a strong 
cold front moving in early on Thursday bringing a risk for
showers and a low risk for storms.

Summer warmth continues into Wednesday, but with a substantial 
decrease in humidity levels (e.g. aftn dewpoints in the upper 
50s to mid 60s) with westerly non-convergent flow offering dry 
weather. Partly sunny with highs in the mid to upper 80s and 
lows in the lower to mid 60s. 

A rather strong mid/upper trough and surface cold front moves
through Southern New England on Thursday. This frontal system
ushers in a true substantial change in airmass. Ordinarily, that 
would point to an active day, but the timing is the biggest
mitigating factor, as the front looks to reach the eastern MA
coast by early afternoon per loose global model consensus. Thus 
current expectation is for minimal to weak diurnal instability 
and an attendant low risk for thunderstorms, but if the front 
ends up slower than current thinking then the risk for storms 
would increase to go along with the risk for strong storms. 
Partly to mostly cloudy skies with highs in the lower 80s, with 
dewpoints falling through the afternoon and evening into low-mid
50s post- frontal, and lows in the 50s to around 60. 

KEY MESSAGE 3...Nice stretch of later-summer weather Friday 
into the weekend.

Main story for Friday into the weekend is a much cooler and
drier airmass that entrenches itself over the Northeast. Cool
advection brings 850 mb temps down to around +8 to +10C,
supportive of highs in the 70s to lower 80s with mostly 
sunny/partly cloudy skies and dewpoints falling into the 40s. 
Overall a nice stretch of late- summer weather if slightly 
cooler than normal for mid August. Next chance for showers or 
storms could arrive by late Sunday or Monday but the timing is 
still a question mark.

&&

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

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

00z TAF Update: 

Tonight: High confidence. 

VFR. Hazy skies due to transported smoke well aloft from
wildfires in eastern Washington was handled with BKN250 decks 
in TAFs through overnight, but no reductions to visbys are 
expected. Westerly flow at ACK should mitigate mist/fog 
development. W/WNW winds around 10 kt decrease to light NW by 
daybreak. 

Monday: High confidence overall but moderate on timing TSRA and
seabreezes. 

Mainly VFR; hazy-looking skies from smoke should clear out but
could return again by late afternoon. TSRA looks to develop late
in the day, starting as soon as 20-21z at BDL and ORH, then move
E/ESE through 02z, and these could be strong with brf IFR 
visbys and strong winds. Indicated VCTS for BDL/ORH as these 
two TAF sites have best shot at TSRA with PROB30 at PVD. Have 
left out of remaining TAF sites due to low confidence. Light NW
winds flip to SW around 5-10 kt; BOS looks to seabreeze to an
ESE direction around 5-10 kt, but it could be short-lived than 
a typical seabreeze with SW winds around 10 kt shown by 21z. 

Monday Night: High confidence. 

Outside of weakening TSRA through 03z, VFR prevails. SW winds
shift to W around 5-10 kt after TSRA ends/moves offshore. 

KBOS Terminal...Moderate confidence in TAF. BKN250 for hazy 
conditions aloft from WA wildfire smoke. VFR prevails, seabreeze
tomorrow around 15z but end timing to SW could be shorter than a
typical seabreeze. SHRA/TSRA possible after 23z Mon but too 
low- confidence to include in TAF.

KBDL Terminal...Moderate confidence in TAF. BKN250 for hazy
conditons aloft from WA wildfire smoke. VFR prevails, though
better shot at TSRA after 20z. Storms could be strong with gusty
winds and brief IFR visbys. 

Outlook /Tuesday through Friday/...

Tuesday through Wednesday: VFR. 

Wednesday Night: VFR. Chance SHRA, slight chance TSRA.

Thursday: VFR. Breezy. Chance SHRA, slight chance TSRA.

Thursday Night: VFR. 

Friday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Monday Night... High Confidence.

Winds briefly turn WNW this evening with a weak cold frontal  
passage before returning to SW by late Monday morning. Local sea
breezes along the east coast of MA. Relatively light seas across
the waters through Monday Night.

Outlook /Tuesday through Friday/...

Tuesday through Wednesday: Winds less than 25 kt. 

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

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers, slight chance of thunderstorms. 

Thursday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Slight chance of rain showers. 

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

&&

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

&&

$$

DISCUSSION...Belk/Loconto
AVIATION...Belk/Loconto
MARINE...Belk/Loconto