234
FXUS61 KLWX 011326
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
926 AM EDT Wed Jul 1 2026
.WHAT HAS CHANGED...
No planned changes to headlines this morning. Coordination
expected this afternoon to upgrade to an Extreme Heat Warning,
with additional Heat Advisories needed for the mountains.
&&
.KEY MESSAGES...
- (1) Extreme heat builds over the region through the
Independence Day holiday weekend.
- (2) Thunderstorm chance increase through this weekend, with
an increased risk for severe thunderstorms Friday into the
Independence Day weekend.
&&
.DISCUSSION...
KEY MESSAGE 1...Extreme heat builds over the region through the
Independence Day holiday weekend.
Today will mark the beginning of a near record breaking heatwave
across the region. Based off of current forecasts, DC and
Baltimore could potentially tie their longest ever stretches of
100 degree days in a row (the record is 4 days at both locations).
Whether or not those records are ultimately tied will depend on
where temperatures reach both today and Saturday, when high
temperatures are forecast to be right around 100. Thursday and
Friday look to be near locks for high temperatures over 100
degrees. IAD could potentially challenge daily record high
temperatures each day through Saturday, while DCA and BWI could
challenge their daily record highs Thursday through Saturday.
For more historical context, see the climate section at the
bottom of the forecast discussion.
On the synoptic scale, a strong upper level ridge/closed
anticyclone will build overhead today through Friday, bringing a
very hot and humid airmass at lower levels along with it. This
upper ridge will start to slowly break down heading into this
weekend, which will open the door for the development of
thunderstorms across the region (see key point 2 below).
In terms of specifics, temperatures are forecast to climb into
the upper 90s to around 100 today at lower elevations, with
dewpoints holding in the upper 60s to lower 70s. This will yield
heat indices of 100-105 to the west of the Blue Ridge, and
105-110 further east. Heat Advisories are in effect for all
locations today, with the exception of the Blue Ridge and
Alleghenies.
The peak of the heat will build in for Thursday and Friday,
when model guidance shows 850 hPa temperatures soaring to around
24-25 C. This should yield high temperatures between 100 and 105
at lower elevations, which when combined with dewpoints in the
upper 60s and lower 70s will result in peak heat indices around
105-110 to the west of the Blue Ridge, and 110-115 further east.
Extreme Heat Watches are in effect for all locations outside of
the Alleghenies and Blue Ridge for both Thursday and Friday.
It looks as though the heat and humidity will likely hold on
through the weekend as well. However, forecast confidence in the
exact high temperatures starts to decrease a bit, as both
remnant cloud cover from thunderstorms on previous days and
thunderstorms from the day of could impact temperatures. As of
now, the current forecast calls for high temperatures in the
upper 90s/lower 100s at lower elevations on Saturday
(Independence Day), and mid 90s to near 100 on Sunday.
Overnight low temperatures each night will be in the 70s for
most, with lower 80s in the urban centers. As a result, there
will be very little relief from the heat overnight.
KEY MESSAGE 2...Thunderstorm chance increase through this weekend,
with an increased risk for severe thunderstorms Friday into the
Independence Day weekend.
With excessive heat and humidity comes the potential for severe
weather as abundant instability and moisture pool over the region.
Coverage of storms today is expected to be very low (around
15pct), with pronounced capping and ample mid-level dry air
present in forecast soundings. The one area where a storm or two
could potentially form is from DC northeastward toward
Baltimore in the vicinity of the I-95 corridor, where low-level
convergence will be maximized as a background surface trough
overlaps with developing bay/river breezes. The threat appears
most apparent from 4pm to 8pm for a pop up storm to develop.
Elsewhere, dry conditions are expected. An even stronger cap is
forecast on Thursday, resulting in dry conditions for all. If a
storm were to form today, it could potentially be capable of
producing strong downbursts, given the very high CAPE/DCAPE
environment that will be in place.
Upper-level ridging will gradually buckle Friday before flattening
over the weekend into early next week as the broad subtropical
ridge shifts further offshore and a series of shortwave
disturbances pivot through. Timing and coverage of storms have
yet to be determined given the placement of synoptic/mesoscale
features. With that said, looking at scattered strong to severe
thunderstorms mainly during the afternoon and evening period
with damaging wind gusts, large hail, heavy rainfall, and
frequent lightning as the main threats. Storms may be of the
pulse variety likely forming along the lee side trough east of
the Alleghenies or residual outflows (i.e the bay/river breeze)
due to the lack shear aloft Friday into Saturday. Of course this
is subject to change based on any disturbances that move
through as the ridge starts to break down. If this were to
occur, we could be looking at more organized and widespread
storm clusters, but confidence in this is low at this time.
Multiple instances of deterministic/ensemble guidance illustrate
this on both Saturday into Sunday as the ridge flattens further.
Google AI WxNext2 along with CIPS/CSU AI probs illustrate this
with rather high probabilities of severe weather this weekend.
As we approach the Independence Day weekend, have a weather
preparedness plan ready to go, especially if you are outdoors (i.e
at a picnic with family or a fireworks show). Plan ahead for any
outdoor activities this weekend, as they are likely to be
interrupted by storms at some point. Have a way to get trusted
warnings, download a radar/lightning app to keep aware of changing
weather conditions, and know when to act. When thunder roars, go
indoors. Lightning can strike up to 15 miles outside of the core
of thunderstorms, so wait 30 minutes after that last rumble of
thunder before resuming outdoor activities. Given the heat in
place, some storms could be quite intense (if they form). From a
historical perspective, prolonged near record heat in summer
often ends in a period of strong storms. Intense storms can
produce hail and high winds in addition to rain and lightning,
so having access to sturdy shelter is important.
&&
.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions are expected through Thursday. Winds will remain
light out of the south early this morning before becoming
west to southwesterly later today into Thursday. Occasional
gusts up to 20 kts are possible both this afternoon and
Thursday afternoon. Afternoon bay/river breezes may cause more
of and east/southeast flow at MTN and potentially BWI/DCA.
These same breezes may also touch off an isolated shower or
thunderstorm at the same aforementioned locations although
confidence remains low at this time.
Prevailing VFR conditions are generally expected on both Friday and
Saturday. Intermittent sub-VFR conditions return Friday afternoon
and evening and again during the afternoon/evening periods this
weekend as thunderstorm chances increase. Should thunderstorms
materialize, some could become severe resulting in erratic changes
in wind speed and directions, potentially exceeding 50 knots.
Additionally, storms would come with the likelihood of frequent
lightning and the chance for some hail. Timing will generally be
during the mid-late afternoon through evening hours each day, with
further west areas earlier and the metros later.
&&
.MARINE...
SCAs remain in effect today due to southerly channeling. Gusts
of 25-30 kts are possible within the main channel of the bay
this afternoon and evening. Additional channeling is possible
Thursday into the weekend although intensity gradually drops
off each day. A pop up shower or t-storm cannot be ruled out
along the western shore of the bay this afternoon/evening due to
the bay breeze. If this were to materialize SMWs, may be needed
to encompass this threat.
Thunderstorm chances increase Friday afternoon and especially by
Saturday afternoon. With any storms will come the chance for erratic
and strong wind gusts, potentially in excess of 50 knots, as well as
frequent lightning and hail. Timing of storms is still a bit
uncertain, but should generally be during the mid-late afternoon
through the evening hours, as is typical with summer convection.
&&
.CLIMATE...
There is a significant heat risk this week. The numbers below
aren`t a forecast, but rather a reference for historical context
for comparison. Latest forecast: weather.gov/lwx.
==================================================================
*** ALL-TIME RECORD HIGHS ***
==================================================================
Baltimore 107 (set on Jul 10, 1936)
Washington 106 (set on Jul 20, 1930 + Aug 06, 1918)
Sterling-Dulles Airport 105 (set on Jul 22, 2011)
Baltimore Downtown 108 (set on Jul 07, 2012 + Jul 22, 2011)
Annapolis 106 (set on Aug 06, 1918)
Hagerstown 105 (set on Jul 14, 1954)
Martinsburg 112 (set on Jul 11, 1936)
Charlottesville 107 (set on Sep 07, 1954 + 3 other times)
==================================================================
*** ALL-TIME RECORD WARM LOWS ***
==================================================================
Baltimore 83 (set on Aug 05, 1930 + 2 other times)
Washington 84 (set on Jul 24, 2011 + 2 other times)
Sterling-Dulles Airport 79 (set on Aug 08, 2007)
Baltimore Downtown 88 (set on Jul 22, 2011 and Jul 10, 1993)
Annapolis 92 (set on Jul 07, 1994)
Hagerstown 86 (set on Jun 15, 1899)
Martinsburg 86 (set on Jul 21, 1930)
Charlottesville 85 (set on Aug 07, 1918)
==================================================================
*** JULY MONTHLY RECORD HIGHS ***
==================================================================
Baltimore 107 (set on Jul 10, 1936)
Washington 106 (set on Jul 20, 1930)
Sterling-Dulles Airport 105 (set on Jul 22, 2011)
Baltimore Downtown 108 (set on Jul 07, 2012 + Jul 22, 2011)
Annapolis 105 (set on Jul 21, 1930 + Jul 02, 1901)
Hagerstown 105 (set on Jul 14, 1954)
Martinsburg 112 (set on Jul 11, 1936)
Charlottesville 107 (set on Jul 10, 1936 + Jul 20, 1930)
==================================================================
*** JULY MONTHLY RECORD WARM LOWS ***
==================================================================
Baltimore 83 (set on Jul 21, 1930)
Washington 84 (set on Jul 24, 2011 + 2 other times)
Sterling-Dulles Airport 78 (set on Jul 24, 2010 + Jul 08, 2010)
Baltimore Downtown 88 (set on Jul 22, 2011 + Jul 10, 1993)
Annapolis 92 (set on Jul 07, 1994)
Hagerstown 83 (set on Jul 24, 2010)
Martinsburg 86 (set on Jul 21, 1930)
Charlottesville 84 (set on Jul 22, 1930)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: Jul 01
==================================================================
Baltimore 103 (1901) | 80 (1933 + 1901)
Washington 102 (1901) | 79 (1977)
Sterling-Dulles Airport 96 (2012) | 72 (2017 + 3)
Baltimore Downtown 101 (2012) | 82 (2012)
Annapolis 103 (1901) | 79 (1945 + 1901)
Hagerstown 100 (1901) | 74 (2017 + 1977)
Martinsburg 102 (1933) | 74 (1933)
Charlottesville 101 (2012 + 1945) | 78 (1901)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: Jul 02
==================================================================
Baltimore 103 (1901) | 80 (1901)
Washington 101 (1898) | 79 (2012 + 1872)
Sterling-Dulles Airport 98 (1966) | 75 (2022)
Baltimore Downtown 102 (1966) | 84 (2002)
Annapolis 105 (1901) | 80 (1901)
Hagerstown 100 (1966) | 74 (2018 + 1901)
Martinsburg 102 (1933 + 1931) | 75 (1933 + 1901)
Charlottesville 100 (1954) | 76 (1910)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: Jul 03
==================================================================
Baltimore 104 (1898) | 80 (1898)
Washington 101 (1966 + 2) | 80 (2018)
Sterling-Dulles Airport 103 (1966) | 73 (2018 + 2)
Baltimore Downtown 102 (1997) | 82 (2018 + 1983)
Annapolis 100 (1901) | 84 (1896)
Hagerstown 102 (1966) | 76 (2002)
Martinsburg 102 (1941 + 1911) | 74 (1980)
Charlottesville 100 (1966 + 1954) | 79 (1911)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: Jul 04
==================================================================
Baltimore 100 (2002 + 2) | 78 (1911)
Washington 100 (1919) | 80 (2018 + 2002)
Sterling-Dulles Airport 97 (2002 + 1999) | 75 (2018)
Baltimore Downtown 101 (2002 + 1990) | 83 (2002)
Annapolis 98 (1999) | 81 (2018)
Hagerstown 100 (1966 + 1919) | 76 (2018)
Martinsburg 103 (1898) | 76 (1999)
Charlottesville 100 (2012) | 78 (1919)
-----------------------------------------------------------------
Number of Consecutive Days Max Temp >=100
Area (obs site) Records since
------------------------------------------------------------------
Baltimore (BWI) 4 days July 14-17,2024 & July 19-22,1930
Washington (DCA) 4 days July 14-17, 2024 & July 5-8, 2012
Sterling-Dulles (IAD) 2 days July 7-8, 2012, July 21-22, 2011
July 6-7, 2010, July 16-17, 1997
Baltimore Downtown (DMH) 5 days July 3-7, 2010 & July 7-11, 1993
Annapolis (NAK) 1 day July 21, 2019, July 7, 2012,
July 22, 2011, June 29, 1959
Hagerstown (HGR) 3 days July 5-7, 2010
Martinsburg (MRB) 6 days June 1-6, 1925
Charlottesville (CHO) 5 days July 4-8, 2012
Period of Record (POR) context...
Area (obs site) Records since
------------------------------------------------------------------
Baltimore (BWI) Jan 1872
Washington (DCA) Jul 1872
Sterling-Dulles Airport (IAD) Jan 1960
Baltimore Downtown (DMH) Jul 1950
Annapolis (NAK) Jan 1894
Hagerstown (HGR) Jan 1899
Martinsburg (MRB) Jan 1891
Charlottesville (CHO) Jan 1893
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Heat Advisory until 8 PM EDT this evening for DCZ001.
Extreme Heat Watch from Thursday morning through Friday
evening for DCZ001.
MD...Heat Advisory until 8 PM EDT this evening for MDZ003>006-008-
011-013-014-016>018-503>508.
Extreme Heat Watch from Thursday morning through Friday
evening for MDZ003>006-008-011-013-014-016>018-502>508.
Heat Advisory until 8 PM EDT this evening for MDZ502.
VA...Heat Advisory until 8 PM EDT this evening for VAZ025>031-
036>040-050-051-053>057-501-502-504>506-526-527.
Extreme Heat Watch from Thursday morning through Friday
evening for VAZ025>031-036>040-050-051-053>057-501-502-
505-506-526-527.
WV...Heat Advisory until 8 PM EDT this evening for WVZ051>053.
Extreme Heat Watch from Thursday morning through Friday
evening for WVZ050>053-055-502-504.
Heat Advisory until 8 PM EDT this evening for WVZ050-055-502-
504-506.
MARINE...Heat Advisory until 8 PM EDT this evening for ANZ530.
Small Craft Advisory from 2 PM this afternoon to 11 PM EDT
this evening for ANZ530-535-536.
Extreme Heat Watch from Thursday morning through Friday
evening for ANZ530.
Small Craft Advisory until 2 AM EDT Thursday for ANZ531>534-
537>541-543.
Small Craft Advisory until 11 PM EDT this evening for ANZ542.
&&
$$
DISCUSSION...DHOF/CJL/KJP/EST
AVIATION...DHOF/CJL/KJP/EST
MARINE...DHOF/CJL/KJP/EST
NWS LWX Office Area Forecast Discussion