035
FXUS66 KMTR 011931
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1231 PM PDT THU OCT 1 2026
..NEW SHORT TERM, LONG TERM, FIRE WEATHER
KEY MESSAGES
UPDATED AT 1224 PM PDT THU OCT 1 2026
- WARM TO HOT TEMPERATURES THROUGH THE NEXT SEVEN DAYS
- HAZARDOUS HEAT FOR MOST INLAND LOCATIONS THIS WEEKEND
- MILD OVERNIGHT LOWS IN THE HIGHER ELEVATIONS WILL LIMIT RECOVERY
- MINOR COASTAL FLOODING AT HIGH TIDE FOR BAYSHORE LOCATIONS ON
THE SAN FRANCISCO, SAN PABLO, AND MONTEREY BAYS THROUGH FRIDAY
SHORT TERM
ISSUED AT 1224 PM PDT THU OCT 1 2026
(THIS EVENING THROUGH FRIDAY NIGHT)
RIDGING, RIDGING, RIDGING... A BASIC SUMMARY OF THE WEATHER PATTERN
ACROSS THE WESTERN UNITED STATES IN THE SHORT AND MEDIUM TERMS. WE
ARE IN THE MIDDLE OF AN EXTENDED PERIOD OF TEMPERATURES WARMER THAN
SEASONAL AVERAGES AND RATHER COMPRESSED MARINE LAYERS, MEANING THAT
THE STRATUS DECK WILL REMAIN CONFINED TO THE IMMEDIATE COAST DURING
THE DAYTIME AND EXPAND INTO THE NORTH BAY VALLEYS, THE SF AND
MONTEREY BAY REGIONS, AND THE NORTHERN SALINAS VALLEY OVERNIGHT, BUT
KEEP THE INTERIOR VALLEYS GENERALLY CLEAR. HIGH TEMPERATURES TODAY
AND FRIDAY RANGE FROM THE MIDDLE 80S TO MIDDLE 90S INLAND, THE UPPER
90S ACROSS THE WARMEST SPOTS OF THE INTERIOR CENTRAL COAST, THE
MIDDLE 70S TO MIDDLE 80S NEAR THE BAYS, AND THE MIDDLE 60S TO LOWER
70S AT THE PACIFIC COAST. THE ONSHORE BREEZE WILL BE RATHER LIGHT
WITH GUSTS OF 20 TO 25 MPH POSSIBLE THROUGH FAVORED GAPS AND PASSES
AND THE NORTHERN SALINAS VALLEY IN THE AFTERNOON AND EVENING HOURS.
REGIONS OF MODERATE HEATRISK ARE EXPANDING ACROSS THE INLAND REGIONS
TODAY AND FRIDAY. THESE CORRESPOND TO A MODERATE RISK OF HEAT-
RELATED ILLNESSES FOR SENSITIVE POPULATIONS, INCLUDING CHILDREN, THE
ELDERLY, PREGNANT WOMEN, PEOPLE WITH CHRONIC ILLNESSES, AND PEOPLE
WHO WORK OR LIVE OUTDOORS WITHOUT ACCESS TO ADEQUATE COOLING OR
HYDRATION. FOLLOW THESE TIPS TO AVOID HEAT EXHAUSTION AND HEATSTROKE:
* STAY HYDRATED AND DRINK PLENTY OF FLUIDS.
* WEAR LIGHTWEIGHT, LIGHT-COLORED CLOTHING.
* REDUCE TIME SPENT OUTDOORS OR STAY IN THE SHADE.
* NEVER LEAVE PEOPLE OR PETS UNATTENDED IN VEHICLES.
* USE SUNSCREEN IF GOING TO THE COAST OR THE POOL.
MINOR COASTAL FLOODING IS POSSIBLE ACROSS THE BAYSHORE LOCATIONS OF
SAN FRANCISCO BAY, SAN PABLO BAY, AND MONTEREY BAY AROUND HIGH TIDE.
UP TO 1.1 FEET OF INUNDATION ABOVE NORMALLY DRY LAND IS EXPECTED,
INCLUDING UP TO 0.7 FT OF SURGE CAUSED BY THERMAL EXPANSION AND SEA
LEVEL RISE SINCE THE SEA LEVEL DATUM (BASICALLY THE POINT WHERE WE
DEFINE AS "SEA LEVEL") WAS SET IN THE 1983-2001 PERIOD. AT THE SAN
FRANCISCO TIDAL GAUGE, HIGH TIDE IS EXPECTED TO BE 1.1 FT ABOVE
NORMAL (6.92 FT MLLW) AT 2:58 PM ON THURSDAY 10/1 AND 0.9 FT ABOVE
NORMAL (6.71 FT MLLW) AT 3:58 PM ON FRIDAY 10/2.
LONG TERM
ISSUED AT 1224 PM PDT THU OCT 1 2026
(SATURDAY THROUGH NEXT WEDNESDAY)
AS THE UPPER LEVEL RIDGE STARTS TO AMPLIFY OVER THE WESTERN UNITED
STATES, A NOTICEABLE WARMUP THIS WEEKEND WILL CAUSE INLAND HIGHS TO
RISE INTO THE MIDDLE 90S TO NEAR 103, WHILE THE BAYS SEE HIGHS
ACROSS THE 80S TO THE LOWER 90S, CREATING HAZARDOUS HEAT CONDITIONS
FOR ANYONE WITHOUT ADEQUATE COOLING OR HYDRATION. MILD OVERNIGHT
LOWS IN THE UPPER 60S TO MIDDLE 70S ACROSS THE HIGHER ELEVATIONS AND
THE MIDDLE TO UPPER 60S IN THE INTERIOR EAST AND SOUTH BAYS WILL
LIMIT THE OPPORTUNITY FOR THE BODY TO RECOVER OVERNIGHT. AS A
RESULT, A HEAT ADVISORY HAS BEEN ISSUED FROM 11 AM SATURDAY TO 10 PM
SUNDAY ACROSS THE SONOMA COASTAL RANGE, THE NORTH BAY INTERIOR
MOUNTAINS, THE SAN FRANCISCO BAY SHORELINE, THE EAST BAY AND SOUTH
BAY, THE SANTA CRUZ MOUNTAINS, THE SANTA LUCIA RANGE, THE INTERIOR
MOUNTAINS OF MONTEREY AND SAN BENITO COUNTIES, AND THE SOUTHERN
SALINAS VALLEY. MEANWHILE, LOCATIONS ALONG THE PACIFIC COAST WILL
FEEL THE INFLUENCE OF A HIGHLY COMPRESSED MARINE LAYER, WITH HIGHS
IN THE UPPER 60S TO MIDDLE 70S AND LOWS IN THE UPPER 50S TO LOWER
60S.
TOWARDS THE BEGINNING OF THE NEXT WORK WEEK, THE RIDGE BEGINS TO
FLATTEN AND TEMPERATURES MAY COOL BY A COUPLE OF DEGREES, BUT
CHANCES FOR HAZARDOUS HEAT REMAIN HIGH AND THE HEAT ADVISORY MAY A
SLIGHT COOLING OF A COUPLE OF DEGREES AT MOST IS POSSIBLE TOWARDS
THE NEXT WORK WEEK AS THE RIDGE BEGINS TO FLATTEN, BUT NEED TO BE
EXTENDED AS THE FORECAST COMES INTO BETTER VIEW. ENSEMBLE MODEL
CLUSTER ANALYSIS CONVERGES ON ANOTHER AMPLIFICATION OF THE RIDGE
TOWARDS THE LATER PART OF THE NEXT WORK WEEK, AND THINGS GET
INTERESTING AGAIN FOR THE SECOND WEEKEND OF OCTOBER (THE 10TH AND
11TH). THE CLUSTERS BEGIN TO SPLIT INTO SCENARIOS THAT KEEP THE
RIDGING IN PLACE OVER THE WESTERN UNITED STATES AND THOSE THAT SHOW
MORE ZONAL FLOW OR EVEN A TROUGH COMING INTO THE WEST COAST. THIS
SPLIT BETWEEN THE CLUSTER SCENARIOS WILL BE INTERESTING TO LOOK AT
THROUGH THE WEEK, AND IS PART OF THE REASON WHY FORECASTS BEYOND THE
NEXT SEVEN DAYS ARE MORE OFTEN DISCUSSED IN TERMS OF PROBABILITIES
THAN DETERMINISTIC LANGUAGE.
AVIATION
(18Z TAFS)
ISSUED AT 1030 AM PDT THU OCT 1 2026
PATCHY LIFR CONDITIONS PERSIST OVER OAK AND HAF WHILE VFR
CONDITIONS HAVE RETURNED TO OTHER TERMINALS. EXPECTING VFR
CONDITIONS TO PERSIST WITH AN INCREASE IN ONSHORE WINDS BY THE
AFTERNOON AND EARLY EVENING HOURS. EXPECTING SIMILAR CONDITIONS AS
THIS MORNING TONIGHT AND INTO FRIDAY AS THE MARINE LAYER LOOKS TO
HOLD AROUND 1,000 FEET IN DEPTH. STRATUS AND/OR FOG WILL BEGIN TO
DISSIPATE BY MID-MORNING ON FRIDAY WITH AN INCREASE IN ONSHORE
WINDS.
VICINITY OF SFO...VFR. ONSHORE WINDS INCREASE UP TO AROUND 15 KT
THIS AFTERNOON BEFORE EASING LATE IN THE EVENING. THE GREATEST
PROBABILITY OF SEEING SUB-MVFR WILL BE BETWEEN 12Z-17Z FRIDAY,
THUS HAVE INCLUDED IT IN THE OFFICIAL FORECAST AT THIS TIME.
SFO BRIDGE APPROACH...GREATER PROBABILITY OF SUB-MVFR BETWEEN
12Z- 17Z FRIDAY. OTHERWISE, SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR. ONSHORE WINDS INCREASE THIS
AFTERNOON BEFORE EASING AFTER SUNSET. THERE IS HIGH CONFIDENCE FOR
SUB-IFR CEILINGS AND/OR PATCHY FOG TO DEVELOP LATE THIS EVENING
AND PERSIST INTO EARLY FRIDAY MORNING. SOUTHERLY WINDS ARE LIKELY
AT SNS FRIDAY MORNING BEFORE SWITCHING ONSHORE BY EARLY AFTERNOON.
MARINE
(TODAY THROUGH TUESDAY)
ISSUED AT 948 AM PDT THU OCT 1 2026
NORTHWEST WINDS WILL DIMINISH AND BECOME GENTLE TO MODERATE BY
LATE THIS MORNING, ALLOWING SEAS TO STEADILY ABATE TO MODERATE BY
FRIDAY. MARINE CONDITIONS IMPROVE FRIDAY INTO THE WEEKEND.
FIRE WEATHER
ISSUED AT 1224 PM PDT THU OCT 1 2026
PERSISTENT RIDGING ACROSS THE WESTERN UNITED STATES LEAVES THE
INTERIOR HOT AND DRY WITH POOR TO VERY POOR DAYTIME HUMIDITY
RETENTION AWAY FROM THE IMMEDIATE COAST, WHILE A COMPRESSED MARINE
LAYER LEAVES OVERNIGHT HUMIDITY RECOVERIES POOR ACROSS THE HIGHER
ELEVATIONS. HOT DAYTIME TEMPERATURES AND MILD OVERNIGHT LOWS IN
THE THERMAL BELTS POSE HAZARDS FOR FIRE CREWS WORKING IN HIGH
ELEVATION AREAS, PARTICULARLY WITHIN THE TIMBER FIRE WHERE MAJOR
TO EXTREME HEATRISK IS POSSIBLE DURING THE WEEKEND. IN
ADDITION, THE HOT AND DRY CONDITIONS LEAD TO RISING ERC VALUES
WITH VALUES IN THE NORTH BAY AND INTERIOR CENTRAL COAST EXPECTED
TO REACH THE 90TH TO 97TH PERCENTILE NEXT WEEK.
DIALH
MTR WATCHES/WARNINGS/ADVISORIES
CA...COASTAL FLOOD ADVISORY UNTIL 6 PM PDT FRIDAY FOR CAZ006-506-508-
529-530.
HEAT ADVISORY FROM 11 AM SATURDAY TO 10 PM PDT SUNDAY FOR CAZ503-
504-508-510-512>518.
PZ...NONE.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...RGASS
MARINE...RGASS
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