Lexington Weather

Lexington, Massachusetts, USA

60°F

9/20/2026 8:51pm

Lexington Conditions: Overcast
Temperature: 59.9°F / 15.5°C
Dew Point: 56.7°F
Relative Humidity: 89%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.95 in Steady
Visibility: 9 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 162359
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
759 PM EDT Wed Sep 16 2026

.WHAT HAS CHANGED...
No significant changes to the forecast.

&&

.KEY MESSAGES...

- Increased humidity and warmer temperatures continue tomorrow.

- Scattered showers possible Thursday evening into Friday
  morning. 

- Rain chances return for the second half of the weekend. There
  remains uncertainty in the details such as coverage, timing,
  amounts.

&&

.DISCUSSION...
KEY MESSAGE 1...Increased humidity and warmer temperatures 
continue tomorrow.

Warmer temperatures with increased humidity continue into
tomorrow as an anomalous moisture plume and higher 925 mb 
temperatures advect into southern New England via SW flow. 
Looking ahead into tonight, the increased moisture and winds 
dropping off in the interior may favor the development of some 
patchy fog, especially in the CT Valley. With 925 mb 
temperatures reaching around 16-19C in the afternoon Thursday, 
high temperatures in the low 80s are a possibility, especially 
in the river valleys. These higher low level temperatures remain
over the region overnight as well with high pressure affixed 
just to our south continuing SW flow; lows tonight will likely 
only drop into 60s as opposed to the areas of 50s and 40s we've 
seen the past few nights. PWATs up to 2.0" and dewpoints in the 
upper 60s will make it feel more humid, too. Despite the 
increased humidity, the region should remain dry for much of the
day tomorrow.

KEY MESSAGE 2...Scattered showers possible Thursday evening 
into Friday morning. Dry during the day Friday.

A weak shortwave trough progresses eastward behind the plume of 
moisture, which will aid in the development of scattered showers
across southern New England. As previously mentioned, latest 
guidance has shown PWATs reaching ans even exceeding 2.0" 
Thursday afternoon/evening. However, we are not anticipating 
widespread downpours as guidance continues to track the stronger
forcing across northern parts of New England. Global models and
a number of the CAMs (with the exception of the NAM) are in 
agreement that higher rainfall totals should generally remain to
our north, and ensemble probabilities also favor this outcome. 
Totals across southern New England should primarily range 
between 0.1" to 0.3" based on the more northern track of the 
wave. The latest CAMs have still shown some elevated instability
Thursday night, so a low chance of some isolated downpours 
cannot be completely ruled out. Totals could also increase 
slightly if the wave were to end up tracking a little further 
south, but the general consensus is that the greatest forcing 
will remain to our north and we could generally expect a few 
tenths of an inch.

Following this system, drier air pushes back in with NW flow,
which will aid in clearing skies through the day and bringing 
temperatures back to a more seasonable range. 

KEY MESSAGE 3... Rain chances return some time late Saturday
night into Monday morning. There remains uncertainty in the 
details such as coverage, timing, amounts. 

A high pressure should move across northern New England
Saturday, then over the North Atlantic Sunday. This should 
clear the path for a low pressure to move from the lower Great 
Lakes south of New England late some time late Saturday night 
into Monday. This will likely be our next period of rainfall. 
However, the timing is not yet finalized, especially with a high
pressure over the ocean. Would not be surprised if a slower 
timing develops.

There is also a question about how much rainfall we can expect 
across our region. High pressure over eastern Canada may nudge 
far enough south to pus the ultimate storm track far enough 
south where we could wind up dry Tuesday into Wednesday. 
Assuming this occurs, total rainfall amounts could be limited to
a general 1-2 inches by Monday afternoon. Otherwise, with a 
nearly stationary front close to the south coast of New England 
could trigger some showers right into mid week.

&&

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

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

Tonight...High confidence.

VFR outside of areas of patchy fog, where MVFR/IFR visibilities
are possible. SW winds near 8-12 kts, with the higher end of 
the range towards the Cape and Islands. Winds become lighter to 
even calm for some areas across the interior tonight. Patchy 
fog in the valleys and other terminals that often see fog (ORH, 
BED mainly) may develop in the early morning hours between 08z 
and 12z, burning off quickly after sunrise. Mid-level cloud 
deck begins to move in overnight into early Thursday morning. 

Thursday...Moderate confidence.

VFR with areas of MVFR developing in the early afternoon/late
morning hours. Winds at 5-10 kt, shifting more S to SE across 
the region towards 17z for most. Some could see winds more SSW, 
particularly for Cape and Island terminals. Showers may start to
move into the region in the afternoon hours from W to E, with 
chances continuing to increase through the evening.

Thursday Night...Moderate confidence.

MVFR with areas of IFR. Showers push across the region, clearing
towards Friday morning, though MVFR conditions could linger a
bit over the Cape and Islands. Winds generally at 5-10 kt from
the SW, shifting NW towards Friday morning.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Friday through Monday/...

Friday: VFR. 

Friday Night: VFR. Breezy. 

Saturday: VFR. 

Saturday Night: VFR. Chance SHRA.

Sunday: Mainly VFR, with areas MVFR possible. Breezy. SHRA
likely.

Sunday Night through Monday: VFR. Breezy. 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.

High pressure continues along with SW winds at 10-15 kt into 
tomorrow. Gusts just under 20 kt are possible in the afternoon 
and evening hours. Chances for showers over the waters increase 
Thursday night, especially for northern parts of the eastern 
waters. Seas remain at 2-3 ft, though areas of the southern 
waters may approach 4 ft heading into Friday morning.

Outlook /Friday through Monday/...

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

Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft. 

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

Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft. 

Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers. 

Sunday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers. 

Monday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. Chance of rain showers.

&&

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

&&

$$

DISCUSSION...Belk/Hrencecin
AVIATION...Belk/Hrencecin
MARINE...Belk/Hrencecin