Lexington Weather

Lexington, Massachusetts, USA

79°F

7/12/2026 2:29pm

Lexington Conditions: Mostly cloudy
Temperature: 79.3°F / 26.3°C
Dew Point: 59.0°F
Relative Humidity: 50%
Wind: Calm, 10-min avg: Calm, gust: 1 mph
Barometer: 30.11 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 052333
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
733 PM EDT Sun Jul 5 2026

.WHAT HAS CHANGED...
A Flood Watch has been expanded into Rhode Island and parts of
southeast Mass.

&&

.KEY MESSAGES...

- Confidence still increasing in the potential for bands of 
  heavy rainfall and even some flash flooding starting late 
  tonight but more likely Monday into Tuesday. The greatest risk
  area right now remains in northern CT where recent heavy rain
  has fallen and a Flood Watch remains in effect and has been 
  expanded. 

- Summer warmth & humidity return for the latter half of the 
  week. A few showers and thunderstorms possible by Friday to 
  Saturday.

&&

.DISCUSSION...
KEY MESSAGE 1...Confidence still increasing in the potential 
for bands of heavy rainfall and even some flash flooding 
starting late tonight but more likely Monday into Tuesday. The 
greatest risk area right now remains in northern CT where recent
heavy rain has fallen and a Flood Watch remains in effect and 
has been expanded.

To start with the highest confidence, we look at antecedent 
conditions. Heavy rainfall yesterday impacted mainly northern 
CT, especially southern Hartford County. Areas where soil 
moisture is approaching 50 percent is roughly northern CT into 
the southern half of RI and into the EWB area. Similarly 6 hr 
FFG is lowest across southern Hartford, Tolland, and Windham 
Counties, with values generally at or below 3 inches. Farther 
north and east that increases to around 4 to 5 inches.

Also higher confidence is the timing of precip. There is a 
chance that heavy rain could begin this evening, but as of this 
writing, CAM guidance wants to focus that more towards Long 
Island Sound than northern CT. Mon into Tue looks more favorable
for rounds of heavy rain/showers to push into northern CT and 
parts of RI. 

More moderate confidence will be the location and amounts of 
heavy rain. One thing I can say for sure is that all available 
guidance, from global to convection allowing mesoscale weather 
models have some impressive QPF numbers. Many include max QPF 
values of 7 inches or more. One such piece of guidance is the 
05.12z HREF. 24 hr max QPF is in the 7-10 inch range. From past 
experience and local research, the HREF max QPF usually does 
occur even if the blend struggles to pinpoint the location. So I
think it is reasonable to prepare for rainfall amounts on that 
order. Best guess at this range would be in the BDL to PVD 
corridor somewhere, but anywhere south of the Mass Pike would be
wise to keep an eye on trends. With that in mind I feel more 
comfortable expanded the Flood Watch east into RI and the flash 
flooding hotspot of Fall River to cover those higher soil 
moisture areas, and where synoptic forcing do not look 
meaningfully different from CT. 

KEY MESSAGE 2...Summer warmth & humidity return for the latter 
half of the week. A few showers and thunderstorms possible by 
Friday to Saturday. 

There isn't a whole lot more to say about this period. Temps 
will continue to climb until by Fri a few locations may be 
flirting with 90 degrees again. A cold front will approach from 
the northwest and provide a focus for showers and thunderstorms.
At this time the best chances for rain will be northwest of the
forecast area Thu, but by Fri chances will be much better to 
see at least scattered convection across southern New England.

&&

.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...

Today through Monday...Moderate confidence.

VFR conditions continue to prevail with SHRA/TSRA staying west
of the forecast area. Gradually SHRA/TSRA will work their way
east southeast overnight. Unless heavy rain hits a terminal I do
not anticipate MVFR conditions until Mon morning at the
earliest. SHRA/TSRA will be a threat mainly for BDL to ACK
tonight, expanding towards PVD, ORH, and BOS Mon morning. Thru
Mon I expect that MVFR CIGs will start to creep northeastward
and move to cover the forecast area. This along with
increasingly likely SHRA/TSRA. Some of that rain may be locally
heavy, but confidence is too low to add those IFR VIS 
conditions to the TAFs. By Mon evening some IFR CIGs may also
begin to develop as CIGs lower and rain becomes more widespread.
I do think significant areas of fog will also avoid the forecast
area, including ACK. Light southeast winds tonight will turn
more easterly towards morning thru Mon.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Tuesday through Friday/...

Tuesday: MVFR/IFR conditions possible. Breezy. SHRA likely,
slight chance TSRA, patchy BR.

Tuesday Night: Mainly VFR, with local IFR possible. Chance
SHRA.

Wednesday through Wednesday Night: VFR. 

Thursday: VFR. Breezy. 

Thursday Night: VFR. Slight chance SHRA, slight chance TSRA.

Friday: VFR. Breezy. Chance SHRA, chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today and tonight...High confidence.

High pressure over eastern Canada combined with a wave of low 
pressure passing to our south will result in ESE winds this
afternoon and tonight...But the winds/seas should remain below 
small craft advisory thresholds.

Monday...Moderate confidence.

Wave of low pressure passing to our south should result in E wind 
gusts increasing to around 25+ knots across our southern waters. 
Later shifts will likely need to issue small craft advisories for 
our southern waters and we may need to expand them further north 
Monday night.

Outlook /Tuesday through Friday/...

Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Seas up to 5 ft. Rain showers likely, slight chance
of thunderstorms, patchy fog. Local visibility 1 to 3 nm.

Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Chance
of rain showers. 

Wednesday through Wednesday Night: Winds less than 25 kt. Seas
up to 5 ft. 

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

Thursday Night: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain showers. 

Friday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain showers, slight chance of thunderstorms.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from 2 AM EDT Monday through Tuesday afternoon for 
     CTZ002>004.
MA...Flood Watch from 2 AM EDT Monday through Tuesday afternoon for 
     MAZ020.
RI...Flood Watch from 2 AM EDT Monday through Tuesday afternoon for 
     RIZ001>008.
MARINE...Small Craft Advisory from 11 AM Monday to 2 AM EDT Tuesday for 
     ANZ235-237.
     Small Craft Advisory from 11 AM Monday to 2 PM EDT Tuesday for 
     ANZ255-256.

&&

$$

DISCUSSION...Boatman/Legro
AVIATION...Legro
MARINE...Boatman