Lexington Weather

Lexington, Massachusetts, USA

69°F

8/12/2026 1:41am

Lexington Conditions: Clear
Temperature: 69.4°F / 20.8°C
Dew Point: 63.0°F
Relative Humidity: 80%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.73 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 081848
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
248 PM EDT Sat Aug 8 2026

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

&&

.KEY MESSAGES...

- Diurnal shower and thunderstorm chances remain a threat today.
  Heat and humidity slowly trending down during Sunday. Dry
  weather expected Sunday.

- Next week trending not as hot and not as humid each day, and 
  possibly slightly cooler than normal by Fri into next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Diurnal shower and thunderstorm chances remain a
threat today. Heat and humidity slowly trending down during
Sunday. Dry weather expected Sunday.

Typical convective environment across southern New England this
afternoon. One of limited bulk shear and modest CAPE values.
Isolated thunderstorms already developed across portions of
northern MA, with more across eastern NY state. The greatest
risk for stronger thunderstorms will be across western MA and
CT. Still thinking this risk will diminish after sunset, 
although thunderstorms could still persist into the later 
evening. The greatest threat would be straight-line wind damage.

Drier weather anticipated for Sunday. Favored the lowest dew
point guidance due to expectation of a W wind across the
interior. That said, still thinking it will take into the
afternoon before dew points reach the lower 60s to upper 50s
across the interior. Towards the Cape and islands, dew points
should struggle to get much below 70 until some time Sunday 
night. 

KEY MESSAGE 2...Very warm and humid weather continues through 
Wednesday. Daily shower and storm chances each day too, but 
lesser of a chance Sunday.

Overall pretty persistent summer weather pattern really right 
through Wednesday, with enhanced quasi-zonal flow in mid levels 
interacting with summerlike temperatures and humidity levels. 

Warm temperatures and elevated but not really oppressive 
humidity levels (dewpoints in the mid to upper 60s) can be 
expected to continue through Wednesday. General sameness to 
925-850 mb temps each day, only slightly cooling by a degree or 
two from Sunday through Wednesday, which supports highs in the 
mid/upper 80s and heat indices in the lower to middle 90s. While
not necessarily a hazardous combo of heat and humidity and most
are already acclimatized to the summer warmth, thus not looking
at headline- level heat, it is still an extended spell of heat 
indices in the low to mid 90s, so still continue to adequately 
hydrate and take breaks in cooler spaces.

With westerly mostly non-convergent low-level flow and modest 
height rises Sunday, Sunday should end up being a generally dry 
day as will be tough to get enough lift to spark storms. 
Otherwise, daily shower and thunderstorm chances again resume 
for early to mid next week, and with somewhat stronger flow, a 
couple of those storms could become strong or severe in this 
timeframe. The issue is timing the storms out, as has been the 
case most of this week; this is very challenging as any ripple 
in the faster mid-level flow could focus better storm chances 
given the warm and humid weather. At this forecast time horizon 
timing specific day(s) have more storm chances than others is a 
tough ask. Won't be raining and thundering all the time but 
there will be storms to dodge here-and-there. 

Tough to find many areas to improve upon NBM so stayed fairly 
close to outputted NBM forecast values during this period.

KEY MESSAGE 2...Next week trending not as hot and not as humid 
each day, and possibly slightly cooler than normal by Fri into 
next week.

Hudson Bay vortex slowly digs southeast through Ontario and
Quebec next week, and in the process, advects numerous short 
waves into SNE. Each short wave will slowly erode the northwest 
periphery of the western Atlantic subtropical ridge over SNE. 
This will result in a risk of scattered showers/thunderstorms 
each day through Thu. Although, not expecting a washout with 
many hours of dry weather each day. Hence, a typical mid August 
week for SNE. In addition, each short wave passage will result 
in temps and humidity coming down a notch each day. Thus, the 
week will begin with warmer than normal temps along with dew pts
in the 60s. Then finish the week with temps at or slightly 
cooler than normal by Fri, along with dew pts in the 50s! 

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

Through Tonight: Overall high confidence, but lower on TSRA 
timing.

Mainly VFR. Still some uncertainty in timing of TSRA at specific
terminals. Handled most with a PROB30. TSRA dissipates late this
evening. South-coastal IFR fog/stratus returning, with VFR
elsewhere.

Sunday and Sunday Night: High confidence.

VFR. General W to SW winds prevail.

KBOS Terminal...Moderate confidence. 

Monitoring for TSRA this aftn/evening. Best estimate in TAF, but
cannot dismiss the idea of an earlier start.

KBDL Terminal...Moderate confidence. 

Monitoring for TSRA this aftn/evening. Best estimate in TAF, but
cannot dismiss the idea of an earlier start.

Outlook /Monday through Thursday/...

Monday: VFR. 

Monday Night: VFR. Slight chance SHRA.

Tuesday through Wednesday: VFR. 

Wednesday Night: VFR. Slight chance SHRA.

Thursday: VFR. Breezy. 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 Sunday Night... High Confidence.

High pressure remains positioned off of the east coast. This 
will continue to produce a SW flow across the waters this
weekend. Gusts to 20 kts possible over the southern waters 
today, but should remain under SCA levels.

Outlook /Monday through Thursday/...

Monday: Winds less than 25 kt. 

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

Tuesday: Winds less than 25 kt. 

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

Wednesday: Winds less than 25 kt. 

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

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

&&

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

&&

$$

DISCUSSION...Belk/Nocera
AVIATION...Belk/Nocera
MARINE...Belk/Nocera