175
FXUS61 KLWX 230757
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
357 AM EDT Mon Jun 23 2025
.SYNOPSIS...
A prolonged period of very hot weather is expected through the
middle of the week as a large ridge of high pressure builds
over the eastern United States. A risk of showers and
thunderstorms returns during the middle to latter portions of
the week as a frontal system approaches from the north. This
system meanders nearby late in the week and into the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
A seasonably warm and humid air mass is in place early this
morning with current temperatures in the 70s to near 80 degrees
in the metro hubs. GOES-19 nighttime satellite imagery shows
skies mainly cloud free across the local area. Offshore of the
New Jersey coast, a mid-level cloud deck continues to drift
westward in time. Such clouds could reach northeastern Maryland
in the next few hours, but no impacts are anticipated as these
track through.
Based on temperature/dew point trends, do not expect much change
heading toward sunrise. A warm and humid start to the day will
give way to near record breaking heat today as a strong upper
ridge is parked overhead. With 500-mb heights running around
597-dm, this is easily around 2 standard deviations above
mid/late June climatology. Pronounced subsidence under this dome
of warm air aloft will generally squash most cloud development.
However, like previous days, a fair weather cumulus field likely
bubbles up given the degree of heat and humidity at the surface.
Multi-model and statistical forecast guidance support a
forecast high around 100 degrees. This is in agreement with the
850-mb temperatures running between 22-24C which dry
adibatically mixed down favors triple digit heat. Daily records
may be broken for both daytime high temperatures as well as for
the warm overnight lows. See the Climate section below for more
details on local records and when they occurred.
A mixture of Extreme Heat Warnings and Heat Advisories are in
place over the region today from 11 AM until 9 PM. Generally
speaking, these heat-related warnings cover the northern
Shenandoah Valley eastward into the D.C. and Baltimore metros,
while stretching south along I-95 and over southern Maryland.
Heat Advisories span central Virginia Piedmont back into the
central Shenandoah Valley and points westward. Higher elevations
remain out of any such heat headline. The combination of heat
and humidity will raise heat indices into the 100 to 110 degree
range.
As usual, the biggest question mark is whether high dew
point air can hold in place despite deep boundary layer mixing.
Depending on model, some show a capping inversion around 850-mb
which would inhibit dry air entrainment near the top of the
layer. Either way, extended outdoor exposure to today`s elements
may increase the risk of heat illness. Ensure to have a way to
stay cool and hydrated, while wearing light colored clothing.
Little to no relief is expected into tonight as winds become
nearly calm. A warm and humid air mass will hold low
temperatures well into the 70s, with low 80s across D.C. and
Baltimore. Elevated humidity levels keep heat indices in the 80s
to near 90 degrees in the warm spots. The potential for heat
illnesses will continue in this environment.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
There is very little change in the synoptic pattern heading into
Tuesday as the 597-dm anticyclone remains overhead. Widespread
upper 90s are likely with some spotty 100 to 102 degree readings
possible. Even for mountain locations, highs will still be well
into the 80s to near 90 degrees. This may prove challenging for
some areas that traditionally do not have air conditioning.
Extreme Heat Watches remain in place on Tuesday across the
northern Shenandoah Valley and all locations east of the Blue
Ridge Mountains. Heat Advisories are currently in place over the
central Shenandoah Valley northward into portions of the eastern
West Virginia panhandle into western Maryland. Heat indices
again push into the 100 to 110 degree range. For those currently
in a watch area, a decision to go with either an Extreme Heat
Warning or Heat Advisory will be made later today.
With the center of the upper ridge positioned over the area,
large-scale subsidence will largely limit any storm threats.
However, some global guidance attempts to fire off some isolated
convection over the higher terrain. Given the consistent signal
in some models, have added this to the forecast during the late
afternoon to early evening hours. Outside of this possible
development, skies should be mostly sunny amidst ample
summertime humidity. Dew points could be a smidge lower given
forecast soundings show a bit more boundary layer mixing.
Overall conditions remain warm and muggy into Tuesday night with
another round of mid/upper 70s (low 80s inside D.C. and
Baltimore) expected.
Although the upper ridge continues its presence into Wednesday,
forecast models do show heights decreasing by around 2 to 4 dm.
This slight weakening of the ridge may help shave off a couple
of degrees off daytime temperatures. However, despite this
subtle shift, highs are forecast to still punch well into the
90s. A light northwesterly wind continues through the period,
but conditions remain humid over the region. The heat/humidity
combination will yield heat indices into the 100 to 107 degree
range. Additional heat products are likely needed.
Given some subtle weakening of the ridge, shower and
thunderstorm chances return to the forecast on Wednesday
afternoon/evening. Depending on where a west-east oriented
frontal zone sets up to the north, an additional focus for
convective development may emerge. For now, will maintain a 20
to 30 percent chance for thunderstorms before the threat wanes
into the night given the loss of diabatic heating. Wednesday
night`s temperatures could be a couple degrees cooler, but this
still supports widespread 70s (mid/upper 60s in the mountains).
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
The extended stretch of hot and humid conditions, with very warm
overnight temperatures, greatly increases the risk of heat illness.
Therefore, it is imperative to have a plan to stay cool during this
upcoming prolonged period of heat.
Mid-level ridging persists through Thursday, then the ridge finally
begins to break down Friday into the weekend. Extreme heat and
humidity on Thursday give way to somewhat closer to normal
heat/humidity, but it will still be plenty hot going into the
weekend. The breakdown of the ridge gives way to zonal flow aloft,
with a few weak passing shortwaves. The Bermuda High builds in
across the Southeast and maintains a steady stream of moist
southerly flow into the Mid-Atlantic.
Daily showers and thunderstorms are likely each afternoon to evening
from Thursday through the weekend. Ample instability will be present
given high heat and humidity, with daily temperatures well into the
90s and heat index values making a run at the century mark. There
will be very little flow to organize storms, meaning localized
flooding could be a concern.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
A strong upper ridge remains parked over the region through at
least the first half of the week. VFR conditions are likely
through Tuesday night in this setup. An isolated shower or
thunderstorm could fire off Tuesday afternoon/evening, but these
should be tied to the terrain. A better chance for a few storms
is possible on Wednesday as the ridge weakens a tad. This could
lead to a few restrictions if occurring around one of the TAF
sites. Otherwise, winds remain on the lighter side (10 knots or
less), with prevailing winds out of the northwest.
VFR conditions prevail through the end of this week. Showers
and thunderstorms return to the forecast Thu/Fri, that could
result in brief periods of sub-VFR conditions.
&&
.MARINE...
Wind gusts up to around 10 to 15 knots are possible early this
morning over the more southern waters. However, expect these to
stay below advisory thresholds. Otherwise, gradients remain on
the weaker side with a strong ridge aloft. Overall wind fields
through mid-week should yield gusts to around 5 to 10 knots.
Although wind directions will be variable at times, the
prevailing direction should be out of the northwest. Some storm
chances emerge by Wednesday afternoon/evening which could impact
portions of the waterways.
Winds remain light through the end of this week. Still, mariners
should be mindful for any isolated strong afternoon and evening
thunderstorms may pop up, and bring an attendant threat of
gusty winds and lightning.
&&
.TIDES/COASTAL FLOODING...
Current tidal anomalies are sitting between 0.25 to 0.50 feet.
This is keeping water levels slightly elevated for the more
sensitive tidal sites. At this point, only Fort McHenry and
Annapolis are slated to reach Action stage during the next
couple of astronomical high tides. Expect the shift to
northwesterly winds to lower anomalies over the next day or two.
&&
.CLIMATE...
Here are some daily high temperature records during the June
23-27, 2025 timeframe:
A `+` sign indicates multiple years currently hold that record.
***MONDAY, JUNE 23RD, 2025***
LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 99F (2024) 81F (2024)
Washington-Dulles (IAD) 98F (2024) 78F (2024)
Baltimore (BWI) 98F (2024) 81F (2024)
Baltimore Inner Harbor (DMH) 99F (2024)+ 83F (2024)
Martinsburg (MRB) 100F (1934) 72F (2024)+
Charlottesville (CHO) 100F (1894) 76F (1996)
Annapolis (NAK) 98F (1988) 77F (2011)
Hagerstown (HGR) 98F (2010) 78F (2024)
***TUESDAY, JUNE 24TH, 2025***
LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 100F (2010) 78F (2010)
Washington-Dulles (IAD) 97F (2010) 73F (2010)
Baltimore (BWI) 100F (2010) 76F (2010)+
Baltimore Inner Harbor (DMH) 101F (2010)+ 82F (2010)
Martinsburg (MRB) 97F (1943) 70F (2024)+
Charlottesville (CHO) 101F (1930) 74F (1914)
Annapolis (NAK) 97F (2000)+ 81F (1896)
Hagerstown (HGR) 96F (2010)+ 75F (2010)
***WEDNESDAY, JUNE 25TH, 2025***
LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 100F (1977) 76F (2010)+
Washington-Dulles (IAD) 97F (1966) 71F (1981)
Baltimore (BWI) 99F (1997) 77F (1949)+
Baltimore Inner Harbor (DMH) 104F (1997) 79F (1998)+
Martinsburg (MRB) 99F (1997) 72F (1949)
Charlottesville (CHO) 99F (1997) 77F (1951)
Annapolis (NAK) 98F (2000)+ 78F (1997)+
Hagerstown (HGR) 98F (1952) 75F (1949)
***THURSDAY, JUNE 26TH, 2025***
LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 101F (1952) 77F (1952)+
Washington-Dulles (IAD) 99F (2024) 72F (2023)+
Baltimore (BWI) 99F (2024)+ 80F (1952)
Baltimore Inner Harbor (DMH) 104F (1998) 83F (1952)
Martinsburg (MRB) 102F (1943) 75F (1949)
Charlottesville (CHO) 99F (1998) 78F (1952)
Annapolis (NAK) 98F (1998)+ 81F (1952)
Hagerstown (HGR) 98F (1954)+ 75F (1952)
***FRIDAY, JUNE 27TH, 2025***
LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 99F (2010) 80F (1952)
Washington-Dulles (IAD) 100F (1964) 72F (2021)+
Baltimore (BWI) 100F (2010) 78F (1949)+
Baltimore Inner Harbor (DMH) 101F (2010) 83F (1998)
Martinsburg (MRB) 101F (1943) 75F (1952)
Charlottesville (CHO) 100F (1952) 79F (1952)
Annapolis (NAK) 98F (1911) 79F (1943)
Hagerstown (HGR) 99F (2010) 77F (1952)
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for DCZ001.
Extreme Heat Watch from Tuesday morning through Tuesday
evening for DCZ001.
MD...Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for MDZ003>006-008-011-013-014-016>018-503>508.
Extreme Heat Watch from Tuesday morning through Tuesday
evening for MDZ003>006-008-011-013-014-016>018-503>508.
Heat Advisory from 11 AM this morning to 9 PM EDT this evening
for MDZ502.
Heat Advisory from 11 AM to 9 PM EDT Tuesday for MDZ502.
VA...Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for VAZ027>031-053>057-502-505-506-526-527.
Extreme Heat Watch from Tuesday morning through Tuesday
evening for VAZ027>031-036>040-050-051-053>057-501-502-
505-506-526-527.
Heat Advisory from 11 AM this morning to 9 PM EDT this evening
for VAZ025-026-036>040-050-051-501.
Heat Advisory from 11 AM to 9 PM EDT Tuesday for VAZ025-026.
WV...Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for WVZ052-053.
Extreme Heat Watch from Tuesday morning through Tuesday
evening for WVZ052-053.
Heat Advisory from 11 AM this morning to 9 PM EDT this evening
for WVZ050-051-055-502-504-506.
Heat Advisory from 11 AM to 9 PM EDT Tuesday for WVZ050-051-
055-502-504-506.
MARINE...Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for ANZ530.
Extreme Heat Watch from Tuesday morning through Tuesday
evening for ANZ530.
&&
$$
SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...KRR
AVIATION...BRO/KRR
MARINE...BRO/KRR
TIDES/COASTAL FLOODING...BRO
CLIMATE...LWX