Lexington Weather

Lexington, Massachusetts, USA

78°F

8/26/2026 6:18pm

Lexington Conditions: Partly cloudy
Temperature: 78.1°F / 25.6°C
Dew Point: 64.9°F
Relative Humidity: 64%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.96 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 261900
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
300 PM EDT Wed Aug 26 2026

.WHAT HAS CHANGED...

No significant changes to the forecast.

&&

.KEY MESSAGES...

- Scattered thunderstorms, some of which could be severe late 
  Thursday, with a few hit and miss thunderstorms possible again
  Friday afternoon. 

- Mainly dry and seasonable weather follows for this weekend
  with comfortable humidity. 

- A period or two of unsettled weather may return early next week 
  with a backdoor cold front in the vicinity of southern New England.
  Large spread/high uncertainty on temps dependent on backdoor
  cold front/s location. 


&&

.DISCUSSION...

KEY MESSAGE 1...Scattered thunderstorms, some of which could be 
severe late Thursday, with a few hit and miss thunderstorms possible 
again Friday afternoon. 

A decent set-up for some strong to severe storms on Thursday, albeit 
better to our west where the better forcing is more likely to 
overlap the favorable dynamics. Even so, especially for western 
MA/CT, particularly along and west of the Connecticut river valley, 
some severe storms are certainly possible in the Thursday afternoon 
to midnight time frame. This comes courtesy of a marginally deep 
upper trough that becomes slightly negatively tilted as it digs into 
the northeast. The trough axis remains west of SNE on Thursday into 
Friday placing us beneath moist SW flow advecting in PWATS of 1.5-2" 
and dewpoints in the upper 60s. This moist flow in the warm sector 
will lead to potential for localized downpours some of which, could 
cause localized flooding. There is a marginal risk (level 1 of 4) 
for flash flooding in western/central MA and CT. This is in addition 
to the marginal severe risk (level 1 of 5) thanks to the 1000-2000 
J/kg CAPE and 0-6km bulk shear. As previously mentioned, the slower 
frontal passage means the better forcing will be to our west, so the 
best chance of damaging storms is west of the CT river valley. The 
greatest threat is from straight line winds and hail, but 0-1km SRH 
values 150-200m2s2 mean a tornado can't be ruled out. By Friday the 
front moves through and some scattered afternoon thunderstorms are 
possible before a much drier airmass drops in. 

KEY MESSAGE 2...Mainly dry and seasonable weather follows for this 
weekend with comfortable humidity. 

High pressure builds in behind the departing shortwave/cold
front for this weekend. The result will be mainly dry and seasonable 
weather Sat into Sun with comfortable humidity. High temps will 
mainly be in the upper 70s and 80s with lows in the 50s to the lower 
60s. 

KEY MESSAGE 3...A period or two of unsettled weather may return 
early next week with a backdoor cold front in the vicinity of 
southern New England. Large spread/high uncertainty on temps 
dependent on backdoor cold front/s location.

Quite a tricky forecast for the first half of next week with a 
backdoor cold front in the vicinity. If we end up on the northern 
side of the front...it will be cool with highs in the upper 60s and 
70s. If we end up south of the backdoor cold front...highs may reach 
85-90+. Given the uncertainty we blended the guidance. Current 
thinking is we may be on the warmer side Mon and then cooler Tue. It 
does seem a decent shot the backdoor cold front temporarily drops 
south into at least part of our region on Tue. But again...high 
uncertainty on temperatures in the Mon through Wed time frame. 

There also will be the risk for some showers at times in the Mon 
through Wed time frame. While we are not expecting a complete 
washout...thinking a round or two scattered showers and perhaps a 
few thunderstorms is reasonable. Timing though remains quite 
uncertain at this point. 


&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Forecaster Confidence Levels...

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

This afternoon...High confidence.

VFR. Light W-SW winds with local seabreezes along portions of 
the very immediate coast. Speeds 6-12 kts. 

Tonight...High confidence. 

VFR. Calm/light SW winds. IFR in patchy ground fog and stratus 
possible late in the typically prone locations. 

Thursday...High confidence.

Mainly VFR. Scattered showers and thunderstorms possible after
18Z with greater risk for western MA/CT terminals. Local MVFR 
possible in any SHRA and TSRA.

Thursday night...High confidence. 

VFR initially then cigs drop to MVFR/IFR for interior terminals
in lingering SHRA/TSRA, mainly through 6-8z. 

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Thursday Night through Monday/...

Friday: VFR. Chance SHRA, slight chance TSRA.

Friday Night: VFR. Breezy. 

Saturday through Saturday Night: VFR. 

Sunday: VFR. Breezy. 

Sunday Night: VFR. Slight chance SHRA.

Monday: Mainly VFR, with local IFR possible. Slight chance
SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Thursday night...High confidence.

Fairly quiet boating conditions with high pressure over the 
waters. Light NW to W winds to start with local seabreezes 
towards the coast late this morning and afternoon. Winds become 
more S to SW tonight, the increase Thursday. By Thursday
evening, rain and thunderstorm chances increase from east to
west through midnight.

Outlook /Thursday Night through Monday/...

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

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

Saturday Night through Sunday: Winds less than 25 kt. 

Sunday Night: Winds less than 25 kt. Slight chance of rain
showers, slight chance of thunderstorms. 

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

&&

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

&&

$$

DISCUSSION...Frank/BW
AVIATION...Frank/BW
MARINE...Frank/BW