946
FXUS66 KMTR 260601
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1101 PM PDT TUE AUG 25 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1242 PM PDT TUE AUG 25 2026
- A SHALLOW MARINE LAYER WILL KEEP COASTAL CONDITIONS NEAR
NORMAL THROUGH THURSDAY
- SEASONABLY WARM AND VERY DRY CONDITIONS CONTINUE ABOVE 1000
FEET AND ACROSS THE FAR INTERIOR THROUGH THURSDAY
- PATTERN CHANGE FRIDAY INTO THE WEEKEND BRINGS COOLER
TEMPERATURES AND MODERATE POTENTIAL FOR TROPICAL MOISTURE
UPDATE
ISSUED AT 836 PM PDT TUE AUG 25 2026
STRATUS IS BEGINNING TO DEVELOP AT THE IMMEDIATE COASTAL REGIONS
WITH HIGH CLOUDS FLOWING OVER THE REGION. SOME UNCERTAINTY
REMAINS OVER THE EXTENT OF THE STRATUS TONIGHT, PARTICULARLY
REGARDING A POSSIBLE COMPRESSION OF THE MARINE LAYER THAT HAS NOT
BEEN OBSERVED AS OF YET, BUT WILL CONTINUE TO MONITOR OBSERVATIONS
THROUGH THE EVENING.
DIALH
SHORT TERM
ISSUED AT 1242 PM PDT TUE AUG 25 2026
(THIS EVENING THROUGH WEDNESDAY NIGHT)
REGIONAL SATELLITE IMAGERY IS SHOWING STRATUS RETREATING TO THE
IMMEDIATE PACIFIC COASTLINE WITH ABUNDANT SUNSHINE EXPECTED ACROSS
THE INTERIOR THIS AFTERNOON. MEANWHILE, PASSING HIGH CLOUDS ALSO
PERSIST AND ARE MOVING NORTHEASTWARD ACROSS REGION. THUS, INTERIOR
TEMPERATURES WILL WARM INTO THE 80S TO MID 90S AND UP TO AROUND
105 DEG F IN THE WARMEST INTERIOR PARTS OF MONTEREY COUNTY.
PERSISTENT ONSHORE AND A SHALLOW MARINE LAYER WILL KEEP
TEMPERATURES NEAR SEASONAL AVERAGES NEAR THE COAST. BREEZY ONSHORE
WINDS ARE FORECAST TO DEVELOP BY THIS AFTERNOON AND EVENING, WITH
GUSTS UP TO 20 TO 35 MPH ALONG THE COAST AND IN THE FAVORED
VALLEYS AND PASSES.
TONIGHT, EXPECTING STRATUS TO RETURN INLAND LATE THIS EVENING AND
INTO THE INTERIOR VALLEYS BY WEDNESDAY MORNING. HOWEVER, THE
INLAND EXTENT MAY BE LESS THAN PREVIOUS DAYS AS THE MARINE LAYER
COMPRESSES SLIGHTLY.
FOR WEDNESDAY, A SLIGHT UP TICK IN TEMPERATURES AS THE RIDGE
BUILDS FURTHER WEST ACROSS THE DESERT SOUTHWEST. AS SUCH,
TEMPERATURES WILL BE SOME 5-10 DEGREES F ABOVE AVERAGE WITH 10-20
DEGREES F ABOVE AVERAGE IN THE FAR INTERIOR AND HIGHER ELEVATIONS
ABOVE 1000 FEET. WE ARE STILL EXPECTING WARM AND VERY DRY
CONDITIONS ABOVE THE MARINE INFLUENCES WITH LITTLE TO NO OVERNIGHT
HUMIDITY RECOVERIES THROUGH THURSDAY. SEE THE FIRE WEATHER
SECTION FOR THE IMPLICATIONS FOR LOCAL FIRE WEATHER CONCERNS.
LONG TERM
ISSUED AT 1242 PM PDT TUE AUG 25 2026
(THURSDAY THROUGH NEXT MONDAY)
AFTERNOON TEMPERATURES WILL BE SLIGHTLY COOLER ON THURSDAY AS A
TROUGH OF LOW PRESSURE APPROACHES THE WEST COAST, HOWEVER 850 MB
TEMPERATURES WILL REMAIN BETWEEN 23-26 DEGREE C. THE COOLING TREND
WILL BECOME MORE NOTICEABLE FRIDAY AND MORESO INTO THE UPCOMING
WEEKEND AND EARLY NEXT WEEK AS THE TROUGH DEEPENS OVER THE PACIFIC
NORTHWEST. THURSDAY NIGHT INTO FRIDAY, WE ARE EXPECTING MID/UPPER
LEVEL TROPICAL MOISTURE TO ADVECT NORTHWARD ACROSS THE BAY AREA
AND CENTRAL COAST. THIS WILL DEFINITELY INCREASE HIGH CLOUD COVER
AND ALSO RESULT IN AN INCREASED POTENTIAL FOR HIGH-BASED RAIN
SHOWERS AND/OR THUNDERSTORMS. HOWEVER, THE LACK OF INSTABILITY
LOOKS TO BE THE LIMITING FACTOR FOR THUNDERSTORMS. WE ARE
MONITORING THIS CLOSELY AT THIS TIME.
EXPECTING BREEZIER CONDITIONS WITH THE DEEPENING TROUGH OFF OF
THE WEST COAST. GUSTS ARE FORECAST TO BE BETWEEN 25 TO 35 MPH
NEAR THE COAST AND IN THE FAVORED VALLEYS, GAPS, AND PASSES BY
FRIDAY AND INTO THE WEEKEND. BY MONDAY, TEMPERATURES ARE FORECAST
TO BE SOME 5-15 DEGREES F BELOW SEASONAL AVERAGES WHICH MATCHES
WITH THE CPC'S 6-10 DAY TEMPERATURE OUTLOOK.
AVIATION
(06Z TAFS)
ISSUED AT 1100 PM PDT TUE AUG 25 2026
VFR PREVAILS WITH THE EXCEPTION OF KSFO AND KHAF WITH STRATUS
COVERAGE NOT NEARLY AS EXTENSIVE AS EXPECTED. 00Z KOAK BALLOON
MEASURED A RELATIVELY WEAK MARINE LAYER AROUND 1000FT SIMILAR TO THE
BODEGA BAY PROFILER. GUIDANCE IS STRUGGLING WITH THE CURRENT
CONDITIONS LEADING TO A LOW CONFIDENCE FORECAST THROUGH WEDNESDAY
MORNING.
VICINITY OF SFO...KSFO IS CURRENTLY IFR, HAVE DECIDED TO MAINTAIN
THAT UNTIL APPROXIMATELY 15Z. AS MENTIONED ABOVE, THIS IS A LOW
CONFIDENCE FORECAST WITH GUIDANCE STRUGGLING WRT STRATUS PUSHING
INLAND OVERNIGHT. LOW LEVEL BOUNDARY LAYER FLOW CHANNELING INTO
THE BAY AREA SHOULD PROVIDE SOME COVERAGE THROUGH MID-MORNING WITH
KOAK EXPECTED TO SEE IFR CEILINGS AROUND OR SHORTLY AFTER
MIDNIGHT TONIGHT, AND LIFT WITH SIMILAR TIMING AS KSFO.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...DIFFICULT FORECAST WITH CURRENT GUIDANCE
NOT PICKING UP ON THE CURRENT CLEAR SKIES. UNLIKE THE NORTH BAY
AND BAY AREA, THERE IS ACTUALLY A WEAK FETCH OF OFFSHORE FLOW
THROUGH THE OVERNIGHT. THAT COMBINED WITH SOME MID/HIGH LEVEL
CLOUD COVER LIMITING RADIATIONAL CLOUD TOP COOLING, MAY REMAIN
VFR THROUGH THE TAF PERIOD. FOR NOW HAVE A CHANCE OF IFR CEILINGS
DEVELOPING AROUND SUNRISE WITH PEAK RADIATIONAL COOLING POTENTIAL
AND LESS MID/HIGH LEVEL CLOUD COVER EXPECTED. IF CEILINGS
EVENTUALLY DEVELOP AFTER SUNSET, THEY SHOULD LIFT BY MID-MORNING.
MARINE
(TONIGHT THROUGH NEXT MONDAY)
ISSUED AT 836 PM PDT TUE AUG 25 2026
MODERATE NORTHWEST BREEZES WITH STRONG GUSTS CONTINUE TONIGHT AS
MODERATE WIND DRIVEN SEAS PREVAIL THROUGH THE WEEK. NORTHWEST
WINDS BECOME FRESH TO STRONG WEDNESDAY INTO THE WEEKEND. A LONG
PERIOD SOUTHERLY SWELL APPROACHES OUR COASTAL WATERS BY THE END OF
THE WEEK.
FIRE WEATHER
ISSUED AT 1202 AM PDT TUE AUG 25 2026
NEAR-CRITICAL FIRE WEATHER CONDITIONS CONTINUE THROUGH THURSDAY FOR
ELEVATIONS ABOVE 1000 FEET AS WARM AND DRY CONDITIONS CONTINUE
ACROSS THE REGION. HUMIDITY RECOVERIES REMAIN POOR TO VERY POOR IN
THE HIGHER ELEVATIONS, WITH NOCTURNAL DRYING EXPECTED WITHIN THE
SANTA LUCIA RANGE. BREEZY CONDITIONS WILL DEVELOP EACH AFTERNOON AND
EVENING, BUT NOT FOR A LONG ENOUGH PERIOD TO TRIGGER ANY FIRE
WEATHER PRODUCTS. SPECIFICALLY REGARDING THE TIMBER FIRE VICINITY,
OBSERVATIONAL DATA SUGGESTS THAT SOUTHWESTERLY WINDS FROM THE
PACIFIC OCEAN OVER THE RIDGETOPS ARE HELPING TO MOISTEN THE AIR,
WITH NOCTURNAL DRYING BEING OBSERVED AS THE WINDS DIMINISH AND EVEN
TURN FAINTLY OFFSHORE OVERNIGHT. THIS HAS LED TO AN UNUSUAL
SITUATION WHERE DAILY MAXIMUM RELATIVE HUMIDITY VALUES HAVE BEEN
OBSERVED DURING THE DAYTIME. SMOKE TRANSPORT FROM THE TIMBER FIRE
WILL CONTINUE TO PEAK IN THE AFTERNOON AND EVENING WITH THE PLUME
SPREADING TOWARDS THE SALINAS AREA. FRIDAY INTO THE WEEKEND, A
PATTERN CHANGE SHOULD ALLOW FOR SOME RELIEF AS AN UPPER LEVEL TROUGH
COMES INTO THE REGION BRINGING COOLER TEMPERATURES AND A DEEPER
MARINE LAYER.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 9 AM PDT THURSDAY FOR PIGEON PT TO PT
PINOS 0-10 NM-PIGEON PT TO PT PINOS 10-60 NM-PT ARENA TO PT
REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM-PT PINOS TO PT
PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...RGASS
LONG TERM....RGASS
AVIATION...JM
MARINE...DIALH
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