❰ Current Conditions

Excessive Heat Watch
EXCESSIVE HEAT WATCH IN EFFECT FROM TUESDAY AFTERNOON THROUGH FRIDAY EVENING

Excessive Heat Watch issued June 16 at 2:25AM EDT until June 21 at 7:00PM EDT by NWS Boston/Norton MA

* WHAT...Dangerously hot conditions with afternoon heat index values up to 105 possible.

* WHERE...In Connecticut, Hartford CT and Tolland CT Counties. In Massachusetts, Central Middlesex MA, Southeast Middlesex MA, Western Norfolk MA, Western Essex MA, Eastern Franklin MA, Eastern Hampden MA, and Eastern Hampshire MA Counties.

* WHEN...From Tuesday afternoon through Friday evening.

* IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events.

* ADDITIONAL DETAILS...There will not be much relief during the overnight hours...as Heat Indices will only drop into the 70s.

* PRECAUTIONARY/PREPAREDNESS ACTIONS...Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.

Expires: June 16 at 5:00 PM EDT
NWS Area Forecast Discussion
Area Forecast Discussion
National Weather Service Boston/Norton MA
1003 AM EDT Sun Jun 16 2024

.SYNOPSIS...
High pressure will bring dry and pleasant Father's Day. 
Dangerous heat and humidity arrives on Tuesday and peak in the 
Wednesday through Friday time frame. Near to record breaking 
high temperatures are possible with afternoon Heat Indices 
between 95 and 105 degrees. Not much relief at night with near 
record breaking warmest low temperatures and heat indices still 
in the 70s.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

10 AM Update...

Forecast is on track with a beautiful morning in progress across
southern New England. We're just starting to see some of those
high clouds make their way into the region, and this will
continue to filter more sun through the afternoon as clouds
increase. 

Previous Discussion...

* Plenty of sunshine with highs mainly in the middle-upper 70s 
  but upper 60s to lower 70s on the immediate eastern MA coast

Upper level ridge and high pressure continues to build into the
region from the west. A passing weak 500mb shortwave will bring
some high clouds and filtered sunshine to the region late in 
the day. All in all, today will be another gorgeous day with 
highs mainly in the middle to upper 70s...but developing sea
breezes will hold afternoon highs in the upper 60s to lower 70s
along portions of the immediate coast.. Dewpoints mainly in the
40s will make it feel very comfortable this afternoon. Winds 
will also be also be light as they turn from northerly to 
southerly late in the day. Sea breezes along the coast will 
develop this morning into the afternoon.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Tonight:

High pressure remains over the region leading to another night of 
good radiational cooling. Clear skies and light winds will allow for 
overnight lows to drop into the low 50s. The only thing keeping the 
region from dropping into the 40s again is dewpoints will be on the 
rise due to light southerly flow. With rising dewpoints, there could 
be isolated patches of fog overnight.

Tomorrow:

Upper level ridge continues to build over the region with high 
pressure still overhead. 850mb temps will be on the rise to +15C 
ahead of the dangerous heat and humidity expected mid week. Winds at 
the surface will also continue to increase out of the south at 10 to 
15 mph, gusting 20-25 mph. This will bring high temperatures back up 
into the low to mid 80s with dewpoints in the low 60s. Winds should 
be strong enough to keep sea breezes at bay except near the south 
coast where southerly winds will enhance the sea breeze and bring 
cooler daytime temps in the 70s to southern RI and SE MA.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Key Points...

* Dangerous Heat & Humidity Tue through Fri...Near Record High Temps
* Excessive Heat Watch Issued...Potential for Heat Indices of 105+
* Main risk for scattered showers/t-storms Fri and/or next weekend

Details...

All the model guidance continues to be very consistent and in 
excellent agreement on dangerous heat and humidity beginning 
Tuesday...peaking in the Wed through Fri time frame. The models 
indicate 500 mb height fields approaching 600 dm...which is rarely 
seen in our region and a strong signal for the potential of record 
heat. This is also supported by the NAEFS & EPS Situational 
Awareness tables...which indicates several parameters outside the 
models climatology. That is another strong signal for the potential 
of a rare/highly unusual weather event...in this case being heat and 
humidity.

The ensemble guidance supports near record highs well into the 
90s...perhaps touching 100 degrees in spots. If that were to 
occur...we would challenge all time record highs for the month of 
June in spots. The only possible relief would be if localized sea 
breeze are able to develop along portions of the very immediate 
coast. Either way...the main story will be several days of dangerous 
heat & humidity. Afternoon Heat Indices will reach into the 95 to 
105+ degree range. There will not be much relief at night with heat 
indices only dropping into the 70s. 

We opted to issue an Excessive Heat Watch in the Tue through Fri 
time frame for the Lower CT River Valley as well as the lower 
elevations of northeast MA/Merrimack Valley away from the immediate 
coast. This is where our confidence is highest in the potential for 
105+ Heat Indices. This Watch might certainly need to be expanded in 
later forecasts...but at the very least Heat Advisories will 
eventually be needed away from the immediate south coast, 
Cape/Islands.

The strong upper level ridge will tend to result in mainly dry 
weather for much of the week. That being said...given near record 
high temps we can not rule out mainly diurnally driven widely 
scattered showers/t-storms. The main threat though for scattered 
showers/t-storms will not arrive until Fri and/or next weekend 
depending on when a cold front drops south into the region.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Forecast Confidence Levels:

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

12z TAF Update...

Today: High Confidence.

VFR. Light northerly winds early this morning becoming light S
by early afternoon. Localized sea breezes develop near the 
coasts.

Tonight: High Confidence

VFR, calm/light southerly winds. Low chance for patchy fog to 
develop.

Tomorrow:

VFR. Increasing southerly winds at 10-15 knots, gusting 20-25 
knots. Diurnal cumulus deck likely forms in the afternoon but 
stays near or above 5kft

KBOS TAF...High confidence in TAF.

Light N winds shift to the NE and then a traditional E/ESE sea
breeze by early afternoon. 

KBDL TAF...High confidence in TAF.

Outlook /Monday Night through Thursday/...

Monday Night through Tuesday: VFR. Breezy. 

Tuesday Night: VFR. 

Juneteenth: Mainly VFR, with local MVFR possible. Breezy.
Slight chance SHRA, slight chance TSRA.

Wednesday Night: VFR. Breezy. 

Thursday: Mainly VFR, with local MVFR possible. Breezy. Slight
chance SHRA, slight chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today and tonight

Clear conditions and light southerly winds. Seas around 2-4 
feet.

Monday:

Continued clear conditions with increasing southerly winds at
10-15 knots, gusting 20-25 knots.

Outlook /Monday Night through Thursday/...

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

Tuesday through Wednesday Night: Winds less than 25 kt. 

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

&&

.CLIMATE...
All Time June High Temperature Record (Daily)

BOS - 100 F (06/06/1925, 06/26/1952 and 06/30/2021)
BDL - 100 F (06/26/1952, 06/30/1964)
PVD - 98 F  (06/25/1943, 06/15/1945 and 06/30/1945)
ORH - 98 F  (06/26/1952)

Most recent day of 100 F (or greater) 

BOS - 100 F (07/24/2022)
BDL - 100 F (07/21/2019)
PVD - 100 F (07/28/2020)
ORH - 102 F (07/04/1911)*

* For ORH this is the only 100+ degree day in its period of record.

Daily High Temperature Records... 

June 18th

BOS - 94 F (1907 and 1929)
BDL - 95 F (1957 and 1994)
PVD - 94 F (1929)
ORH - 93 F (1907 and 1929)

June 19th

BOS - 96 F (1923)
BDL - 95 F (1995)
PVD - 94 F (1923)
ORH - 93 F (1923)

June 20th

BOS - 98 F (1953)
BDL - 97 F (2012)
PVD - 95 F (1941)
ORH - 93 F (1953)

June 21st

BOS - 96 F (2012)
BDL - 96 F (1953 and 2012)
PVD - 96 F (1941)
ORH - 91 F (Multi-Years)

Daily Warmest Low Temperatures Records...

June 18th

BOS - 72 F (1929)
BDL - 70 F (1905)
PVD - 72 F (1929)
ORH - 69 F (1905 and 1994)

June 19th

BOS - 73 F (1995)
BDL - 72 F (1929)
PVD - 70 F (1995)
ORH - 72 F (1929)

June 20th

BOS - 78 F (1931)
BDL - 74 F (1931)
PVD - 74 F (1931)
ORH - 72 F (1931)

June 21st

BOS - 80 F (2012)
BDL - 73 F (1923 and 2012)
PVD - 75 F (2012)
ORH - 74 F (1923 and 2012)

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Excessive Heat Watch from Tuesday afternoon through Friday 
     evening for CTZ002-003.
MA...Excessive Heat Watch from Tuesday afternoon through Friday 
     evening for MAZ003-005-006-010-011-013-014.
RI...None.
MARINE...None.

&&