Seabrook, New Hampshire 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

216
FXUS61 KGYX 250754
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
354 AM EDT Wed Jun 25 2025

.SYNOPSIS...
Temperatures come down by 5 to 10 degrees today, but it will
still be hot in places. The relief finally arrives tonight and
Thursday in the form of a backdoor cold front that will move
through tonight. The cooler air will move in on northeast winds
and bring temperatures back down into the 70s. However with the
cooler weather will come higher chances for showers into the
weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
It remains quite muggy out this morning with most still in the
70s and more notably Fryeburg and Augusta still sitting at 80
degrees as of 3AM. Relief is on the way though, but first we`ll
have to deal with another hot day, although not to the "degree"
of yesterday. The strong ridge of high pressure has retreated
slightly to the south and west in response to the weak frontal
boundary still pushing through the area, and temperatures aloft
have come down...but not much.

The not so great news is that the temperatures aloft still support
temperatures south of the mountains reaching the upper 80s to
low 90s. The better news is that the light northerly flow behind
the frontal boundary and high pressure beginning to build in to
the north will carry drier air southward into the region with a
steady drop in dewpoints from south to north through the course
of the day. This will keep heat index values near the actual
air temperature for most areas, and the winds should be light
enough to allow the seabreeze to move ashore bringing the temps
down along the coast, although it won`t probably won`t make it
very far inland.

The exception is portions of southern NH may still see heat indices
around 95F for a brief period where the higher dewpoints hang on a
little longer. I have gone ahead and put out a Heat Advisory for
today for eastern Hillsborough and interior Rockingham counties
where there is more confidence in seeing heat indices around
95F for a few hours. Other locations across southern Nh could
still see heat indices reach the mid 90s, but zone averages
don`t quite reach advisory criteria. Isolated storms with a
gusty wind potential may also develop late this morning through
mid afternoon across southern NH where the moisture is a little
more favorable.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
The cooler airmass moves in tonight as a backdoor frontal
boundary moves through the area while high pressure continues to
build in just to the north. It`s looking like a good night to
leave the windows open with the lower dewpoints and low
temperatures in the 50s to lower 60s. Northern areas may even
see lows in the upper 40s.

Broad high pressure will be stretched across the area to start
out Thursday with mostly sunny skies for most to start the day
except a bit more cloud cover is expected over southern NH where
higher moisture will be. As the day goes on, there is trend in
the models for this higher moisture and the backdoor front to
lift back to the north and east with increasing cloud cover,
but there`s differences in how quickly this occurs among
guidance. So I have not deviated from the NBM on this. Weak
isentropic lift and PVA aloft will also bring back a chance of
showers but only around 20% across the area, except 30% in
southern NH. The return to onshore flow and increasing clouds
could keep some locations in the 60s for daytime highs, but in
general temps should be able to reach the 70s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Evening long term update...01z NBM has been incorporated into
the latest forecast and yielded little change to the overall
idea that cooler and wetter conditions will be the norm Friday
and Saturday. However, locations of heavier precipitation are
hard to pin down at this time as convection will likely be
involved.

Previously...

Overview: High pressure resides to the north as moisture makes
its way into the Great Lakes. Along with it, a reprieve from hot
temperatures. As these features push east, the chance for
showers increases across the southern forecast area into Friday.
The highest rain chances look to fall Friday night into
Saturday as low pressure pushes into Quebec. As this system
exits, warming temperatures but drier conditions look to return.

Friday, low pressure rounds the Great Lakes and pushes into
southern Ontario. Greater moisture advection will be ahead of
this low, and thus increasing rain chances Friday into Saturday.
What begins as showers Friday, will eventually become a
steadier rain for Saturday morning. Greater IVT values push
across the southern Great Lakes and into New England during this
period, and increases the confidence of this steadier rainfall.
This could last through Saturday morning before becoming more
showery for the early afternoon. Daytime highs for Friday and
Saturday may be some 30 degrees cooler than early week. Drier
air behind the low pushes in for late weekend, allowing both
lower rain chances but also increasing temperatures into early
next week.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Mainly VFR today through Thursday. HIE and LEB
could see valley fog through around 11Z and then isolated
showers and storms are possible in the MHT, CON, PSM, and PWM
corridor this afternoon. These could cause brief restrictions,
but with such low coverage have opted to leave out of the 06Z
TAFs and will revisit this on the 12Z set. There will also be a
slight chance of showers Thursday, mainly south of a LEB to PWM
line. Coastal sites will likely see a wind shift with the
seabreeze this afternoon, but it may not quite reach RKD.

Long Term...VFR expected Thursday night and Friday. SHRA
continue with more coverage in the west expected through the day
Friday. A period of lower ceilings will become more probable
Friday night into Saturday as low pressure brings more
widespread RA into the region. Improvement is expected by late
Sat, but uncertainty in exact ceiling and restrictions.

&&

.MARINE...
Short Term...Conditions are expected to remain below SCA levels
through Thursday. North to northwest winds will become south to
southwest this afternoon as a seabreeze develops but direction
could be more variable at times. High pressure builds in north
of the area tonight in Thursday and sends a backdoor cold front
across the waters tonight. Winds become northeasterly overnight
and then east to southeast Thursday afternoon.

Long Term...Conditions will largely fall below SCA for the
period. High pressure to the north and east will keep much of
the incoming moisture to the south Thursday night, but succumb
to westerly flow Friday through Saturday. This will bring low
pressure into Quebec along with a period of rain. NE flow Sunday
may result in increasing wave heights and therefore SCA
conditions towards the end of the period.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...Heat Advisory from 10 AM this morning to 7 PM EDT this evening
     for NHZ012-013.
MARINE...None.

&&

$$

SYNOPSIS...
NEAR TERM...Combs
SHORT TERM...Combs
LONG TERM...Cornwell
AVIATION...
MARINE...