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 Boston / Norton, MA

        
000
FXUS61 KBOX 091833
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
233 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 /18Z SUNDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...

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

Tonight...High confidence.

VFR conditions outside the risk for a brief period of lower 
VSBYS clipping ACK tonight. Otherwise, W winds may gust to 
around 20 knots or so this afternoon.

Monday...High confidence.

VFR. Scattered late afternoon/evening showers or thunderstorms,
with the greatest risk across interior southern New England. SW
winds 5-12 knots but sea breezes possible along portions of the
very immediate coast. 

Monday Night... High confidence.

Continued VFR with light W winds.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

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