808
FXUS61 KLWX 290121
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
921 PM EDT SUN JUN 28 2026
WHAT HAS CHANGED
SCATTERED SHOWERS ARE MOVING SOUTH OVER THE ALLEGHENIES AND
CENTRAL SHENANDOAH VALLEY. OCCASIONAL DOWNPOURS ACCOMPANYING A
FEW OF THESE SHOWERS.
KEY MESSAGES
- (1) A WEAK FRONTAL BOUNDARY WILL LINGER ACROSS THE REGION
THROUGH TONIGHT DELIVERING WAVES OF DOWNPOURS.
- (2) SIGNIFICANT HEAT RISK THIS WEEK HEADING INTO THE
INDEPENDENCE DAY HOLIDAY.
- (3) THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS RETURNS
LATE THIS WEEK INTO THE INDEPENDENCE DAY WEEKEND.
DISCUSSION
KEY MESSAGE 1...A WEAK FRONTAL BOUNDARY WILL LINGER ACROSS THE
REGION THROUGH TONIGHT DELIVERING WAVES OF DOWNPOURS.
BRIEF DOWNPOURS COULD ACCOMPANY A COUPLE OF THE SHOWERS OVER THE
ALLEGHENIES AND CENTRAL SHENANDOAH VALLEY OVERNIGHT. OTHERWISE,
SOME PATCHY FOG COULD DEVELOP IN PLACES OVERNIGHT. SOME FOG MAY
BE DENSE.
UPPER RIDGING WILL START TO BUILD IN FROM THE WEST ON MONDAY AND
TUESDAY. LARGELY DRY CONDITIONS ARE EXPECTED BOTH DAYS, BUT A
STRAY AFTERNOON SHOWER OR THUNDERSTORM COULD POTENTIALLY POP UP
OVER THE HIGHER TERRAIN TO THE WEST OF THE BLUE RIDGE.
TEMPERATURES WILL GRADUALLY START TO WARM, WITH HIGHS IN THE MID
TO UPPER 80S ON MONDAY, AND THEN LOWER 90S ON TUESDAY.
KEY MESSAGE 2...SIGNIFICANT HEAT RISK THIS WEEK HEADING INTO THE
INDEPENDENCE DAY HOLIDAY.
INCREASED CONFIDENCE FOR A PROLONGED PERIOD OF EXTREME HEAT AND
HUMIDITY THROUGH THE INDEPENDENCE DAY JULY 4TH HOLIDAY WEEKEND.
SYNOPTICALLY, SUBTROPICAL HIGH PRESSURE AND A BUILDING UPPER-LEVEL
RIDGE WILL ALLOW TEMPERATURES AND HUMIDITY VALUES TO CLIMB TOWARD
RECORD LEVELS OVER A MULTI-DAY PERIOD MID TO LATE THIS WEEK.
TEMPERATURES WEDNESDAY THROUGH SUNDAY WILL BE THE PEAK OF THE
DANGEROUS HEAT WITH HIGHS FOR MOST IN THE UPPER 90S AND LOWER
100S. HEAT INDICES EACH AFTERNOON WILL RUN BETWEEN 102-108
DEGREES WITH A FEW READINGS AROUND 110 ALONG THE IMMEDIATE I-95
METRO CORRIDOR, WESTERN SHORE OF THE CHESAPEAKE BAY/SOUTHERN
MD, AND DOWN ACROSS THE VA PIEDMONT REGION. MINIMAL RELIEF IS
EXPECTED ACROSS THE MOUNTAINS WITH HIGHS IN THE MID 80S AND LOW
90S AND HEAT INDICES IN THE MID TO UPPER 90S AS THE HEAT PEAKS
MID TO LATE WEEK.
ANOTHER CONCERNING ASPECT OF THIS HEAT WAVE IS THAT THERE WILL BE
VERY LITTLE RELIEF AT NIGHT, WITH WIDESPREAD LOWS IN THE UPPER 60S
TO MID 70S (UPPER 70S-80 URBAN AREAS) WEDNESDAY THROUGH SATURDAY.
WITH THAT SAID, LOOKING AT MAJOR TO EXTREME HEAT RISK ACROSS THE
REGION DURING THIS PERIOD. HEAT HEADLINES WILL LIKELY BE NEEDED AND
EVALUATED AS THE EVENT GETS CLOSER. MORE AT WEATHER.GOV/LWX/HEAT.
KEY MESSAGE 3...THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS
RETURNS LATE THIS WEEK INTO THE INDEPENDENCE DAY WEEKEND.
AS MENTIONED IN KEY MESSAGE 2, HEAT IS A BIG CONCERN THIS WEEK.
HOWEVER, WITH EXCESSIVE HEAT AND INCREASING HUMIDITY TOWARDS THE END
OF THE WEEK, THUNDERSTORMS WILL BECOME A THREAT TOWARDS THE END OF
THE WEEK INTO THE WEEKEND. THIS OCCURS AS THE STRONG UPPER-
LEVEL RIDGE OVER THE REGION EVENTUALLY BEGINS TO BREAK DOWN AND
WE START TO SEE SOME RIPPLES OF UPPER-LEVEL SHORTWAVE ENERGY
MOVE NEARBY. THIS THREAT IS ILLUSTRATED BY CSU/CIPS/NSSL (15-40
PERCENT PROBABILITIES) OUTLOOKS ALONG WITH THE GOOGLE WXNEXT AI
MODEL WHICH SUGGEST THE RISK FOR SEVERE WEATHER DURING THE
THURSDAY JULY 2ND TO SUNDAY JULY 5TH TIMEFRAME. SOMETHING WE'LL
CONTINUE TO MONITOR IN SUBSEQUENT FORECAST SHIFTS GIVEN ALL THE
ONGOING OUTDOOR ACTIVITIES ACROSS THE REGION.
HISTORICALLY, NEAR RECORD SUMMER HEAT OFTEN ENDS WITH WIDESPREAD
STRONG THUNDERSTORM ACTIVITY, AND LATEST GUIDANCE STARTS TO BREAK
DOWN THE HEAT THIS WEEKEND (JULY 4) INTO EARLY NEXT WEEK.
AVIATION /01Z MONDAY THROUGH FRIDAY/
MVFR CEILINGS AND PATCHY FOG APPEAR POSSIBLE AGAIN TONIGHT.
SOME FOG MAY BE DENSE. IMPROVEMENT BACK TO VFR IS EXPECTED ON
MONDAY, WITH PREVAILING VFR CONDITIONS THEREAFTER THROUGH
TUESDAY. WINDS WILL BE LIGHT OUT OF THE NORTHEAST TODAY, LIGHT
OUT OF THE EAST TOMORROW, AND THEN TURN OUT OF THE SOUTH ON
TUESDAY.
VFR CONDITIONS MAINLY EXPECTED WEDNESDAY THROUGH FRIDAY NIGHT. WINDS
SOUTH 5 TO 10 KNOTS EACH DAY. THUNDERSTORM CHANCES INCREASE BY
FRIDAY AFTERNOON/EVENING, A FEW OF WHICH COULD BE STRONG TO
SEVERE GIVEN THE EXTREME HEAT AND HUMIDITY. SUB-VFR CONDITIONS
WILL BE POSSIBLE AT TIMES IN ANY STORMS, ALONG WITH CHANGES IN
WIND SPEED AND DIRECTION.
MARINE
WINDS TURN LIGHT OUT OF THE EAST TO NORTHEAST OVERNIGHT INTO
TOMORROW, BEFORE BECOMING SOUTHERLY ON TUESDAY. BRIEF NEAR SCA
PERIODS OF GUSTS ARE POSSIBLE EACH AFTERNOON AND EVENING. WINDS
MAY REACH MORE SOLID SCA LEVELS IN CHANNELED SOUTHERLY FLOW
TUESDAY AFTERNOON/NIGHT. SOUTHERLY WINDS AROUND 5 TO 10 KNOTS
ARE EXPECTED ON BOTH WEDNESDAY AND THURSDAY. HOWEVER, AS
TEMPERATURES DROP CLOSER TO THE WATER TEMPERATURES IN THE
EVENING/OVERNIGHT, CONDITIONS WILL BE FAVORABLE FOR SOUTHERLY
CHANNELING WINDS CLOSE TO 20 KNOTS. SCAS MAY BE NEEDED DURING
THE EVENING/OVERNIGHT HOURS EACH NIGHT AS THIS PATTERN TAKES
HOLD.
SIMILAR CONDITIONS ARE EXPECTED ON FRIDAY, BUT WITH A RETURN OF
THUNDERSTORM CHANCES. STORMS ON FRIDAY AFTERNOON, SHOULD THEY
DEVELOP, COULD BE QUITE STRONG TO SEVERE. SPECIAL MARINE WARNINGS
MAY BE NEEDED FRIDAY AFTERNOON/EVENING AS A RESULT.
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 02, 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)
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...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
DISCUSSION...KLW/DHOF/EST
AVIATION...KLW/DHOF/EST
MARINE...KLW/DHOF/EST
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