055
FXUS66 KMTR 040451
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
951 PM PDT MON AUG 3 2026
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 1155 PM PDT SUN AUG 2 2026
- MODERATE HEATRISK IN THE INTERIOR THROUGH TUESDAY, BECOMING
PATCHY MIDWEEK
- NEAR CRITICAL FIRE WEATHER THREAT ACROSS THE INTERIOR NORTH AND EAST
BAYS, AND THE DIABLO AND SANTA LUCIA RANGES THROUGH MONDAY
WITH ELEVATED FIRE WEATHER THREAT THROUGH THE WEEK
- WIDESPREAD MODERATE HEATRISK LOOKS TO RETURN FOR THE END OF
THE WORK WEEK.
SHORT TERM
ISSUED AT 1255 PM PDT MON AUG 3 2026
(THIS EVENING THROUGH TUESDAY NIGHT)
NEARTERM:THE SOUTHERLY SURGE CONTINUES TO INCH ITS WAY NORTHWARD
ALONG THE COAST AND FINALLY MADE IT PAST PT REYES. THE SURGE HAS
REALLY TAKEN A BIT OUT OF TEMPERATURES ALONG THE IMMEDIATE COAST
THIS AFTERNOON. 24 HR TRENDS SHOW MANY LOCATIONS ALONG THE
COASTLINE ARE RUNNING COOLER THAN SUNDAY, WHICH ISN'T SURPRISING
WITH NEARBY CLOUDS. ON THE FLIP SIDE, HEAD INLAND AND AWAY FROM
THE SURGE INFLUENCE AND TEMPS ARE SOARING INTO THE 90S AND LOWER
100S. AS SUCH, HEAT ADV REMAINS IN EFFECT THROUGH THIS EVENING FOR
INTERIOR NORTH MTS AND INTERIOR EAST/SOUTH BAYS.
TONIGHT THROUGH TUESDAY NIGHT:
THE SURGE WILL BECOME LESS OF A SURGE AND MORE JUST ONSHORE WITH
MORE STRATUS. MODERATE MARINE LAYER STRATUS COVERAGE FOR INLAND
AREAS TONIGHT. THIS STRATUS WILL BRING SOME RELIEF AND BETTER RH,
BUT ABOVE THE SHALL LAYER WILL REMAIN MILD AND DRY.
INTERESTING SET UP FOR TUESDAY AS THE UPPER LEVEL PATTERN SHOWS A
SLIGHT REBOUND OF THE RIDGE, BUT LOWER SURFACE LEVELS KEEP THE
SOUTHERLY/ONSHORE FLOW. PRETTY HARD TO BET AGAIN STRATUS AND
COOLER SST ALONG THE COAST. AS SUCH, TEMPERATURES FOR TUESDAY WILL
BE WITHIN A FEW DEGREES OF MONDAY, BUT ON THE COOLER SIDE. JUST
ENOUGH TO KNOCK DOWN HEATRISK VALUES TO MODERATE WITH LITTLE TO NO
MAJOR.
TUESDAY NIGHT WILL SEE EVEN MORE STRATUS COVERAGE WITH A SLIGHT
DEEPENING.
ONE FINAL CONCERN FOR THE SHORT TERM WILL BE SMOKE/HAZE. AMPLE
FIRE ACTIVITY ACROSS OR/WA WILL PUSH SOME SMOKE OVER THE COASTAL
WATERS. LONGER RANGE RRFS ACTUALLY BRINGS SOME SMOKE/HAZE TO THE
COASTAL WATERS LATE TUESDAY INTO WEDNESDAY.
LONG TERM
ISSUED AT 1255 PM PDT MON AUG 3 2026
(WEDNESDAY THROUGH NEXT SUNDAY)
RINSE AND REPEAT FOR THE LONG TERM, BUT IN THE OTHER DIRECTION
WITH A GRADUAL WARMING AND DRYING TREND.
UPPER LEVEL HIGH PRESSURE THAT BRIEFLY FLATTENED WILL REBUILD
OVER THE WEST COAST BEGINNING LATE WEDNESDAY LASTING THROUGH AT
LEAST FRIDAY. WHILE THERE IS A SLIGHT REPRIEVE IN TEMPS MID-WEEK
INLAND HEAT AND INCREASING HEATRISK RETURN THURSDAY AND MORE SO
FRIDAY. IN FACT, SOME OF THE GUIDANCE SUGGEST AN AIRMASS
APPROACHING 30C AT 850MB. 30C IS A PRETTY TOASTY AIRMASS, WHICH
WOULD EASILY YIELD MAX TEMPS OVER 100 ACROSS THE INTERIOR. WOULD
ALSO EXPECT MILD OVERNIGHT LOWS IN THE HILLS. IF THIS TREND
CONTINUES WE MAY NEED ANOTHER HEAT ADVISORY.
AVIATION
(06Z TAFS)
ISSUED AT 941 PM PDT MON AUG 3 2026
VFR WILL CONTINUE THROUGH THE FORECAST PERIOD FOR THE INTERIOR
SOUTH BAY TERMINALS, THEN IFR/LIFR DEVELOPING AROUND 10Z FOR THE
NORTH BAY AND BAY AREA TERMINALS. IFR/LIFR CEILINGS RETURNED
EARLIER THAN EXPECTED TO THE MONTEREY BAY SITES AND WILL PERSIST
UNTIL EARLY TUESDAY AFTERNOON.
VICINITY OF SFO...VFR UNTIL AT LEAST MIDNIGHT, WITH HIGH
CONFIDENCE THAT IFR/LIFR CEILINGS WILL DEVELOP OVERNIGHT. GIVEN
THE EARLIER ONSET ACROSS MONTEREY BAY SITES, THERES A SLIGHT
CHANCE THAT STRATUS RETURNS CLOSER TO 08Z THAN 10Z. HIGH
CONFIDENCE THAT IFR CEILINGS PERSIST UNTIL LATE MORNING WITH A
SLIGHT CHANCE OF LINGERING INTO THE EARLY AFTERNOON.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...IFR/LIFR CEILINGS RETURNED A LITTLE
SOONER THAN EXPECTED WITH HIGH CONFIDENCE OF PERSISTING INTO THE
EARLY AFTERNOON. VFR THROUGH THE REMAINDER OF TUESDAY AFTERNOON
ONCE THEY LIFT WITH A SUNSET RETURN TUESDAY EVENING.
MARINE
(TONIGHT THROUGH NEXT SUNDAY)
ISSUED AT 941 PM PDT MON AUG 3 2026
LIGHT TO GENTLE BREEZES HAVE SET IN ACROSS OUR OUTER WATERS WITH
BREEZIER SOUTH WINDS AT TIMES AND PRESSURE GRADIENT FORCED
ONSHORE FLOW ACROSS THE COASTAL WATERS TONIGHT. NORTHWEST SEAS
WILL CONTINUE TO EASE AND BECOME 4-8FT FOR THE REMAINDER OF THE
WORK WEEK. NORTHWEST WINDS BEGIN TO INCREASE AND BECOME MODERATE
BY THE END OF THE WEEK INTO THE WEEKEND, WITH INCREASING SEAS
RESPONDING BY THE WEEKEND.
FIRE WEATHER
ISSUED AT 420 PM PDT MON AUG 3 2026
NEAR CRITICAL FIRE WEATHER CONDITIONS CONTINUE THROUGH THIS
EVENING, WITH ELEVATED FIRE WEATHER CONDITIONS PERSISTING THROUGH
THE MIDDLE OF THE WEEK, AND POTENTIALLY A RETURN OF NEAR CRITICAL
CONDITIONS LATER IN THE WEEK. TEMPERATURES REMAIN AROUND 10 TO 15
DEGREES ABOVE NORMAL ACROSS THE INTERIOR (EXCEPT FOR WEDNESDAY,
WITH NEAR NORMAL TEMPERATURES) THROUGH EARLY NEXT WEEK WITH HIGHS
IN THE UPPER 80S TO 90S. NO MAJOR CHANGES TO THE FORECASTED DRY
CONDITIONS. DAYTIME HUMIDITY RETENTION REMAINS POOR ACROSS THE
INTERIOR (20-30%) WITH HUMIDITY VALUES DROPPING INTO THE 10S
ACROSS THE INTERIOR CENTRAL COAST, EAST BAY HILLS/VALLEYS, AND THE
HIGHER ELEVATIONS. PORTIONS OF THE INTERIOR CENTRAL COAST MAY SEE
DAYTIME HUMIDITY VALUES DROP INTO THE SINGLE DIGITS TUESDAY, THEN
AGAIN TOWARDS THE END OF THE WEEK INTO THE WEEKEND. OVERNIGHT RH
RECOVERY REMAINS POOR AT LOCATIONS ABOVE 2,000 FEET WITH VALUES
BETWEEN 25 TO 40% EXPECTED WITH SOME FAVORED LOCATIONS STRUGGLING
TO REACH EVEN 25%. THIS WILL BE PARTICULARLY TRUE ACROSS THE
MAYACAMAS, HIGHEST PEAKS OF THE EAST BAY HILLS, THE DIABLO RANGE,
THE SANTA CRUZ MOUNTAINS, THE SANTA LUCIA AND GABILAN RANGES.
NOCTURNAL DRYING (RAPID DECREASE IN RH THROUGH THE PRE- DAWN
HOURS) MAY ALSO TRANSPIRE WHICH WILL INCREASE THE BURN PERIOD OR
TIME IN WHICH FIRE BEHAVIOR MAY REMAIN ACTIVE. ENERGY RELEASE
COMPONENT (ERC) VALUES ARE PROJECTED TO CLIMB ABOVE THE THE
PERCENTILE ACROSS THE INTERIOR CENTRAL COAST, MID COAST TO
MENDOCINO (NORTH BAY), AND DIABLO- SANTA CRUZ (DIABLO MOUNTAINS
AND SANTA CRUZ MOUNTAINS) ZONES BY THE MIDDLE OF THE WEEK.
DIURNALLY BREEZY ONSHORE WINDS ARE EXPECTED ALONG THE COAST,
MOUNTAIN GAPS AND PASSES, AND ALONG THE RIDGELINES EACH
AFTERNOON/EVENING. WITH NEAR CRITICALLY DRY CONDITIONS AND ABOVE
NORMAL TEMPERATURES EXPECTED, INDIVIDUALS ACROSS THESE AREAS ARE
ADVISED TO AVOID ACTIVITIES THAT MAY SPARK A FIRE. FIRE CREWS ARE
URGED TO EXERCISE EXTRA CAUTION WHEN EXECUTING ANY PRESCRIBED
BURNS, ESPECIALLY WHERE FUELS, TOPOGRAPHY, AND WEATHER ALIGN.
MTR WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY UNTIL 10 PM PDT THIS EVENING FOR CAZ504-510-
513>515.
PZ...NONE.
SHORT TERM...KR
LONG TERM....KR
AVIATION...JM
MARINE...JM
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO
FOLLOW US ON FACEBOOK, X, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
X.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page