799
FXUS66 KMTR 231757
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1057 AM PDT WED SEP 23 2026
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 1232 PM PDT TUE SEP 22 2026
- WARMING TREND CONTINUES THROUGH THURSDAY
- COOLER CONDITIONS FRIDAY INTO THE WEEKEND
SHORT TERM
ISSUED AT 1103 PM PDT TUE SEP 22 2026 (TONIGHT THROUGH THURSDAY)
MARINE LAYER BETWEEN 1500-2000 FEET DEEP AS OF TUESDAY EVENING.
LOW CLOUDS COVER AREAS FROM POINT REYES SOUTHWARD TO BIG SUR WITH
A DECENT PUSH OF STRATUS IN SF BAY AND THE MONTEREY BAY REGION
INCLUDING SALINAS VALLEY. THERE IS AN INCREASING NORTHERLY
GRADIENT NOW TO ABOUT 5 MB FROM ACV-SFO THAT IS ERODING THE
STRATUS FROM NORTH TO SOUTH FOR THE NORTH BAY. THIS IS OCCURRING
AS HIGH PRESSURE IS TRYING TO NOSE INTO THE REGION FROM THE
SOUTHWEST. 850 MB TEMPS WARMING TO AROUND 20-21 CELSIUS WITH HOT
INLAND TEMPS FOR THE INTERIOR CENTRAL COAST (90S) WITH MAINLY
UPPER 80S TO AROUND 90 FOR THE INTERIOR NORTH/SOUTH/EAST BAYS ON
WEDS AFTERNOON. WITH PERSISTENT ONSHORE WINDS NOT REALLY A LATE
SEPTEMBER SETUP WHERE WE WOULD EXPECT WARM/HOT TEMPS AT THE COAST.
LOOKING AT THE EUROPEAN EXTREME FORECAST INDEX WE SEE NO AREAS OF
INTEREST SUGGESTING THIS IS JUST A TYPICAL WARM LATE SEPT DAY ON
TAP. MODELS HOLD ONTO THE WARM INLAND TEMPS FOR ONE MORE DAY
THROUGH THURSDAY. HOWEVER BY THURSDAY AFTERNOON A STORM WELL TO
OUR NORTH WILL INDUCE A STRONG ONSHORE/WESTERLY PUSH, USHERING IN
A MODERATE TO STRONG AFTERNOON/EVENING SEABREEZE ON THURSDAY THAT
WILL SIGNAL RELIEF FOR THE BAY AREA WHILE THE INTERIOR CENTRAL
COAST REMAINS WARM/HOT THROUGH THURSDAY EVENING.
LONG TERM
ISSUED AT 1103 PM PDT TUE SEP 22 2026 (THURSDAY NIGHT THROUGH
NEXT TUESDAY)
A FAIRLY WELL DEFINED EARLY AUTUMN DRY COLD FRONT PASSAGE WILL PUSH
THROUGH THE REGION THURSDAY NIGHT INTO FRIDAY MORNING. NO PRECIP
IS FORECAST FOR THE BAY AREA AS IT REMAINS CONFINED TO AREAS NORTH
OF CAPE MENDOCINO. HOWEVER, ENOUGH COOLING AND MIXING ALOFT TO
ESSENTIALLY ERODE OR MIX OUT THE MARINE LAYER QUICKLY BY EARLY FRIDAY
MORNING. TEMPS STILL REMAIN SEASONABLY WARM/MILD FRIDAY BUT THE
COOLING TREND WILL HAVE BEGUN. WEATHER THIS WEEKEND LOOKS NICE FOR
THE LAST WEEKEND OF SEPTEMBER. CERTAINLY NO HOT WEATHER WITH
INLAND TEMPS MAINLY 70S TO LOWER 80S SATURDAY/SUNDAY WITH ENOUGH
COLD AIR ALOFT AND MIXING TO KEEP SKIES SUNNY WITH PERHAPS ONLY
SOME PATCHY MORNING LOW CLOUDS NEAR THE COAST AND BAYS.
EARLY LOOK AT NEXT WEEK SHOWS NO SIGNAL FOR PRECIP OR ABNORMALLY
HOT WEATHER AND NO FALL OFFSHORE WIND EVENTS. PATTERN LOOKS PRETTY
ZONAL SUGGESTING TEMPS RUNNING NEAR SEASONAL NORMS.
AVIATION
(18Z TAFS)
ISSUED AT 1055 AM PDT WED SEP 23 2026
MOSTLY VFR CURRENTLY, THE EXCEPTION IS KHAF WHERE LIFR CONDITIONS
PERSIST. VFR IS EXPECTED BY LATE MORNING AND WILL PERSIST UNTIL
LATE THIS EVENING WHEN SUB-MVFR CONDITIONS RETURN TO THE COASTAL
AREAS. THERE CONFIDENCE IS MODERATE FOR COASTAL LOCATIONS TO
RECEIVE SUB- IFR AND LOWER CONFIDENCE FOR THE BAY AREA TERMINALS
EARLY THURSDAY MORNING. ANY LOW CLOUDS OR FOG THAT DOES DEVELOP
WILL CLEAR BETWEEN 1630Z-1730Z THURSDAY.
VICINITY OF SFO...VFR. ONSHORE WINDS ARE FORECAST TO INCREASE
THIS AFTERNOON, YET NO SIGNIFICANT GUSTS EXPECTED. WIND SPEEDS
EASE OVERNIGHT AND INTO EARLY THURSDAY MORNING WITH A LOW
CONFIDENCE FOR SUB-MVFR (10-30% PROBABILITY) YET MVFR IS MORE
LIKELY WITH 20-50% PROBABILITY AT OR AROUND 11Z THURSDAY. ANY LOW
CLOUDS THAT DOES DEVELOP WILL CLEAR BETWEEN 1630Z-1730Z THURSDAY
WITH INCREASING ONSHORE WINDS BY THURSDAY AFTERNOON.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR. ONSHORE WINDS ARE FORECAST TO
INCREASE THIS AFTERNOON BEFORE EASING AFTER SUNSET. THERE IS
MODERATE CONFIDENCE TO SEE SIMILAR CONDITIONS LATE THIS EVENING
AND INTO THE OVERNIGHT AS WE SAW THIS MORNING. THERE IS MODERATE
CONFIDENCE FOR SUB-IFR (30-50% PROBABILITY) LATE TONIGHT INTO
THURSDAY MORNING BEFORE RETURNING TO VFR BY AROUND 17Z THURSDAY.
MARINE
(TODAY THROUGH MONDAY)
ISSUED AT 1055 AM PDT WED SEP 23 2026
NORTHERLY BREEZES WILL REMAIN MODERATE TO FRESH OVER THE OUTER
WATERS. LOCALLY HAZARDOUS CONDITIONS WILL PERSIST FOR SMALL CRAFT
OVER THE OUTER WATERS THROUGH WEDNESDAY NIGHT. WINDS WILL WEAKEN
FURTHER ACROSS ALL WATERS ON THURSDAY. FRIDAY WILL SEE AN INCREASE
IN NORTHWEST WINDS ACCOMPANIED BY SEAS BUILDING BACK UP TO ROUGH,
AND CONTINUING INTO THE WEEKEND.
FIRE WEATHER
ISSUED AT 440 AM PDT WED SEP 23 2026
MARINE LAYER RETURNED AGAIN IMPACTING LOWER PORTIONS OF THE
DISTRICT THIS MORNING WITH EXCELLENT RH RECOVERY. SIMILAR TO
YESTERDAY MORNING PATCHY FOG WILL IMPACT THE N BAY VALLEYS,
MONTEREY PENINSULA AND THE SALINAS VALLEY. UNLIKE YESTERDAY TWO
OTHER NOTABLE DIFFERENCES: THE EXACT FOOTPRINT OF THE MARINE
LAYER IS SLIGHTLY DIFFERENT WITH LESS COVERAGE OVER THE E BAY
VALLEYS AND ALONG THE BIG SUR COASTLINE AND MODERATE TO POOR
RECOVERIES ABOVE THE MARINE LAYER. SPEAKING OF THE DRIER
CONDITIONS ALOFT, RH RECOVERIES ARE 15 TO 50 PCT DRIER DEPENDING
ON LOCATIONS. IN OTHER WORDS, NOCTURNAL DRYING RETURNED.
OTHERWISE, WARMER AND DRIER ACROSS THE BOARD, ESPECIALLY INTERIOR
LOCATIONS.
MM
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT EARLY THIS MORNING FOR
PIGEON PT TO PT PINOS 10-60 NM-PT ARENA TO PT REYES 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT THURSDAY FOR PT ARENA TO PT
REYES 10-60 NM.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PDT THURSDAY FOR PT ARENA TO PT
REYES 10-60 NM.
SHORT TERM...RW
LONG TERM....RW
AVIATION...RGASS
MARINE...RGASS
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