595
FXUS61 KPHI 240759
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
359 AM EDT Tue Jun 24 2025

.SYNOPSIS...
The significant heat wave continues as hot high pressure settles
over the Appalachian region. The high pressure system will
begin to weaken and retreat to the south by the middle to end of
the week. A cold front will bring decreasing temperatures along
with increasing chances for showers and thunderstorms toward
the end of the week. A warming trend will resume over the
weekend, but with temperatures closer to climo.

&&

.NEAR TERM /THROUGH TONIGHT/...
Significant and dangerous heat continues today, with potentially
some of the hottest temperatures in over a decade in some locations.

A strong ridge of high hot and dry pressure will build across the
eastern US through today. Mid level heights, thicknesses, and 850 mb
temperatures contributing to the heat wave will all peak during this
time frame. The center of the ridge will be positioned to our
southwest, which should maximize heat potential locally. At the
surface, winds will be from the west or northwest.
This will add a component of downsloping into the temperature
equation, helping to boost temperatures by a couple degrees. The
pattern is checking a lot of boxes for a set up capable of producing
fairly widespread 100 degree temperatures in our region, perhaps one
of the most favorable patterns in a few years.

For today, temperatures look to be a bit warmer compared to
yesterday, with potential widespread triple digits, though the
pattern will favor dewpoints mixing out reasonably well into the
afternoon hours. This will result in lower humidity, but higher
temperatures, resulting in heat index values not very different than
Monday. Still looking at 100-110 heat indices across the board.
Again, a sea-breeze may try to generate, but likely won`t get too
far inland. Regardless of those details, it`s going to continue to
be very hot!

No changes to the headlines through tonight. Extreme Heat Warnings
remain in effect for almost the entire area with the exception of
the coastal zones for the Delaware Beaches, Jersey Shore and Carbon
and Monroe counties where Heat Advisories are still in place. Around
the Delaware Valley, Lehigh Valley, and northern New Jersey,
temperatures could be the hottest observed in over a decade. There
will be little relief overnight as temperatures tonight are expected
to be around 75 to 80 degrees. Heat tends to have cumulative effects
on the body and we are currently forecasting 3 consecutive days of
95+ and 5-6 days of 90+ taking into account temperatures this past
weekend. Take frequent breaks if outside, and drink plenty of fluids.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Dangerous heat will continue across the area Wednesday.

Ridging aloft will remain in place over the area Wednesday with
very slow height falls anticipated during the day as the ridge
begins to break down some. Afternoon highs will range from the
upper 80s across the Poconos and the coastal strip to the mid-
upper 90s elsewhere. With high humidity remaining, heat indices
at peak heating Wednesday will likely exceed 100 across much of
eastern PA, inland NJ, and the Delmarva, with values near 105
possible. With this in mind, an Extreme Heat Warning will remain
in effect for all but Carbon and Monroe counties, and a Heat
Advisory for Carbon and Monroe, through 8 PM. The Heat Advisory
was also extended into Wednesday for the coastal strip through 8
PM.

With the ridge beginning to break down and a cold front
approaching from the north, a few showers and storms will be
possible (POPs around 20-40%) beginning Wednesday afternoon and
into Wednesday night. With strong surface heating enhancing
low- level instability, gusty winds could occur with any
stronger storms, though marginal lapse rates and weak winds
aloft should temper any severe threat. With the isolated
showers and storms, increased cloud cover, and the approaching
cold front, Wednesday night will be slightly cooler (though
still quite warm). In general, lows are expected to be near 70
in the Poconos and along the coast, and in the low-mid 70s
elsewhere.

Thursday, the ridge will continue to become further suppressed
and continue to shift south of the region as a backdoor cold
front approaches from the north, crossing the region during the
afternoon and eventually clearing the area Thursday night.

Temperature-wise, south of the cold front across portions of
southeastern PA, southern NJ, and the Delmarva, high
temperatures on Thursday are expected to rise into the upper
80s and low 90s. For these areas, it will remain humid, thus
some heat indicies around 100 will be possible again, resulting
in the potential for extended heat headlines. By Thursday night,
with the front through the area, overnight lows will fall back
into the upper 60s to around 70. North of the front,
temperatures across the area will be noticeably cooler with
afternoon highs in the upper 70s to mid 80s and nighttime lows
back down into the low to mid 60s!

As the front crosses the region, scattered showers and storms
will become likely during the afternoon and evening hours.
Similar to Wednesday, marginal lapse rates and winds aloft will
limit severe potential, but isolated instances of gusty winds
could occur with the stronger storms.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
With the backdoor front south of the region on Friday and
prevailing onshore flow from the east to east-northeast, we will
get to enjoy a dramatically cooler day with cloudy skies and
highs only in the upper 60s to upper 70s! A few showers and
perhaps a thunderstorm will be possible as well through the day.
Overnight lows will be cool and in the 60s.

Southwesterly flow returns for the weekend with the backdoor
front retreating northward Saturday morning and high pressure
over the southeast shifting offshore. As a result, temperatures
will begin to warm back closer to climatology over the weekend
and slightly above into Monday. Isolated, primarily diurnally
driven convection, will be possible each day. A more active
weather pattern may begin to take shape Monday and beyond, with
indications of a slightly more amplified upper- air pattern
taking shape.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Through 12z...VFR. West-southwest winds becoming west-northwest
within the next hour or two if they haven`t already, around winds 5
kt or less. High confidence.

Today...VFR. West-northwest winds around 10 kt. Seabreeze possible
near KACY which may cause winds to turn southerly in the afternoon.
High confidence.

Tonight...VFR. West/northwest winds 5 kt or less. High
confidence.

Outlook...

Wednesday through Saturday...Mainly VFR. Brief periods of sub-
VFR will be possible during the afternoon and evening hours each
day in isolated to widely scattered showers and storms.

&&

.MARINE...
No marine headlines through tonight. West/northwest winds will
become southerly this afternoon with the development of a sea-
breeze. Tonight, winds go more west/northwest. Speeds around 10 kt
or less. Seas around 2 feet.

Outlook...

Wednesday through Thursday...No marine headlines expected.
Winds remain below 25 kt and seas below 5 ft. Periods of showers
and storms possible each day beginning Wednesday afternoon, but
significant marine impacts are not anticipated.

Friday...Small craft conditions possible behind a backdoor
front. E to ENE winds gusting 15 to 20 kts and seas building to
3 to 5 feet.

Saturday...No marine headlines expected.

Rip Currents...

For Tuesday, NW winds of 5 to 10 mph turn S in the afternoon
behind developing sea breezes. A weak E to ESE swell around 1
feet will be of little consequence. With light winds and
breaking waves around 1 feet, there will be a LOW risk for the
development of dangerous and life threatening rip currents for
the Jersey Shore and for Delaware Beaches. Little change is
expected for Wednesday so we will continue with a LOW risk of
dangerous rip currents for both the NJ shore and the Delaware
Beaches.

For specific beach forecasts, visit weather.gov/beach/phi

&&

.TIDES/COASTAL FLOODING...
With the New Moon approaching on June 25th, astronomical tides
are expected to increase. Spotty minor tidal flooding was
observed for the immediate coastline and back bays as well as
within Delaware Bay beginning tonight. Cannot rule out the need
for advisories later this week as astro tides peak. No tidal
flooding is expected within the tidal Delaware River or
Chesapeake Bay.

&&

.CLIMATE...
Near record breaking heat is expected across the area through
the middle of the upcoming week. All climate sites except
Wilmington and Georgetown set record highs and all climate sites
except Reading set record warmest low temperatures for June 23rd.

Additionally, Mount Pocono set their all-time record high
temperature for June yesterday (June 23rd). The Atlantic City
Marina and Wilmington tied their all time record warmest low
temperature for June yesterday (June 23rd) as well. Further
records are expected to fall into the week. Below is a look at
the last 100 degree day, daily record high maximum and minimum
temperature for all of our climate sites.

Most Recent 100 Degree Day

Site                              Date/Temperature
Allentown (ABE)          July 22, 2011/104
AC Airport (ACY)         July 21, 2019/100
AC Marina (55N)          July  5, 1999/101
Georgetown (GED)         July 21, 2019/100
Mount Pocono (MPO)       July  3, 1911/103
Philadelphia (PHL)       July 18, 2012/100
Reading (RDG)            June 22, 2024/101
Trenton (TTN)            July 18, 2012/100
Wilmington (ILG)         July 18, 2012/101

Record High Temperatures
                          June 24
Site                  Record/Year
Allentown (ABE)           98/1923
AC Airport (ACY)          99/2010
AC Marina (55N)           95/2002
Georgetown (GED)          97/2010
Mount Pocono (MPO)        92/1914
Philadelphia (PHL)        99/1923
Reading (RDG)             98/1908 & 1923
Trenton (TTN)             98/1894
Wilmington (ILG)         102/1894

Record Warmest Low Temperatures
                          June 24
Site                  Record/Year
Allentown (ABE)           71/2010
AC Airport (ACY)          72/1951, 2013, 2017 & 2024
AC Marina (55N)           72/1924, 2002, 2010, 2011, 2013 & 2020
Georgetown (GED)          74/2010
Mount Pocono (MPO)        66/1960, 1964 & 2002
Philadelphia (PHL)        75/1909, 1921, 1994 & 2020
Reading (RDG)             73/1909, 1994 & 2010
Trenton (TTN)             76/1894 & 2010
Wilmington (ILG)          74/1994

Record High Temperatures
                          June 25
Site                  Record/Year
Allentown (ABE)           98/1923
AC Airport (ACY)          96/1997
AC Marina (55N)           95/1952
Georgetown (GED)          96/1952
Mount Pocono (MPO)        91/1952
Philadelphia (PHL)        98/1952
Reading (RDG)             99/1943
Trenton (TTN)             99/1997
Wilmington (ILG)          98/1894

Record Warmest Low Temperatures
                          June 25
Site                  Record/Year
Allentown (ABE)           74/1923 & 1976
AC Airport (ACY)          80/1950
AC Marina (55N)           75/1997 & 2002
Georgetown (GED)          75/2019
Mount Pocono (MPO)        69/1952
Philadelphia (PHL)        76/1909, 1976 & 2002
Reading (RDG)             75/1943 & 1949
Trenton (TTN)             75/1976
Wilmington (ILG)          75/1976

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Extreme Heat Warning until 8 PM EDT Wednesday for PAZ060>062-
     070-071-101>106.
     Heat Advisory until 8 PM EDT Wednesday for PAZ054-055.
NJ...Extreme Heat Warning until 8 PM EDT Wednesday for NJZ001-
     007>010-012-013-015>023-027.
     Heat Advisory until 8 PM EDT Wednesday for NJZ014-024>026.
DE...Extreme Heat Warning until 8 PM EDT Wednesday for DEZ001>003.
     Heat Advisory until 8 PM EDT Wednesday for DEZ004.
MD...Extreme Heat Warning until 8 PM EDT Wednesday for MDZ012-015-
     019-020.
MARINE...None.

&&

$$

SYNOPSIS...Cooper/MJL/Staarmann
NEAR TERM...AKL/Hoeflich/Staarmann
SHORT TERM...Cooper/MJL
LONG TERM...Cooper/MJL
AVIATION...Hoeflich/MJL
MARINE...Hoeflich/MJL
TIDES/COASTAL FLOODING...
CLIMATE...