811
FXUS66 KMTR 051937
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1237 PM PDT MON OCT 5 2026
..NEW SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 1236 PM PDT MON OCT 5 2026
- HAZARDOUS HEAT CONDITIONS INLAND PERSIST THROUGH THURSDAY,
NEVER LEAVE CHILDREN OR PETS IN UNATTENDED VEHICLES!
- ELEVATED FIRE WEATHER CONDITIONS PERSIST IN THE INTERIOR
THROUGH THURSDAY
- COOLER TEMPERATURES POSSIBLE LATE THIS WEEK
SHORT TERM
ISSUED AT 1236 PM PDT MON OCT 5 2026
(THIS EVENING THROUGH TUESDAY NIGHT)
STRATUS CLOUDS LURK AT THE IMMEDIATE COAST, ASSOCIATED WITH A
SHALLOW MARINE LAYER AROUND 500-1000 FEET THICK, BUT THE REST OF THE
REGION REMAINS HOT THROUGH THE NEXT COUPLE OF DAYS AS RIDGING
PERSISTS ACROSS THE WESTERN UNITED STATES, RIDGING WHICH IS HELPING
COMPRESS THE MARINE LAYER AND PREVENTING ANY SUBSTANTIAL OVERNIGHT
RELIEF FROM REACHING THE HIGHER ELEVATIONS. TO OUR NORTHEAST, HIGH
LEVEL CLOUDS AND CONVECTIVE REMNANTS, ASSOCIATED WITH A PUFF OF
MOISTURE RIDING AN EMBEDDED LOW IN THE LARGER SCALE RIDGING, LINGER
OVER THE NORTHERN SIERRA NEVADA RANGE AND INTO THE NORTHERN SECTIONS
OF THE GREAT BASIN. THIS TIME YESTERDAY, THAT PUFF OF MOISTURE WAS
STREAMING OVER THE BAY AREA, RESULTING IN STREAMING HIGH CLOUDS THAT
CONTRIBUTED TO SOME COOLER (RELATIVELY SPEAKING) CONDITIONS THAN THE
EXPECTATION. TODAY THE SKIES REMAIN CLEAR, AND IT'S POSSIBLE FOR
TODAY'S HIGH TEMPERATURES TO OVERPERFORM YESTERDAY'S, ESPECIALLY
ACROSS THE NORTH BAY. HIGH TEMPERATURES TODAY AND TUESDAY RANGE FROM
THE MIDDLE 90S TO NEAR 106 ACROSS THE INLAND VALLEYS, THE MIDDLE 80S
TO THE LOWER 90S NEAR THE BAYS, AND THE UPPER 60S TO THE LOWER 70S
ALONG THE PACIFIC COAST. MILD OVERNIGHT LOWS IN THE HIGHER
ELEVATIONS, RANGING FROM THE UPPER 60S TO THE MIDDLE 70S, ALONG WITH
WEAK ONSHORE FLOW WILL LIMIT OVERNIGHT RECOVERIES.
A HEAT ADVISORY REMAINS IN EFFECT FOR THE INTERIOR REGIONS,
EXCLUDING THE COASTAL STRIP AND THE NORTHERN SALINAS VALLEY, AS
WIDESPREAD MODERATE HEATRISK BLANKETS THE INTERIOR, CORRESPONDING 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. IN ADDITION, MANY OF THE HIGHER
ELEVATIONS ARE SEEING MAJOR HEATRISK, CORRESPONDING TO A HIGH RISK
FOR HEAT-RELATED ILLNESSES FOR ANYONE WITHOUT HYDRATION OR COOLING.
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.
LONG TERM
ISSUED AT 1236 PM PDT MON OCT 5 2026
(WEDNESDAY THROUGH NEXT SUNDAY)
RIDGING PERSISTS FOR THE NEXT FEW DAYS AND THE HEAT ADVISORY HAS
BEEN EXTENDED TO THURSDAY NIGHT FOR THE INLAND AND BAYSHORE REGIONS.
TEMPERATURES ACROSS THE INLAND VALLEYS REMAIN IN THE MIDDLE 90S TO
NEAR 105 INTO THURSDAY; DESPITE A COUPLE OF DEGREES OF COOLING ON
THURSDAY, HAZARDOUS HEAT LINGERS ACROSS THE REGION AND WIDESPREAD
MODERATE HEATRISK PERSISTS IN THE INLAND REGIONS. PATCHES OF
HEATRISK LINGER INTO FRIDAY ACROSS THE INTERIOR, AND THE HEAT
ADVISORY MAY NEED TO BE EXTENDED IF CONFIDENCE IN HEAT-RELATED
IMPACTS INCREASES.
TOWARDS THE LATTER PART OF THE SEVEN DAY OUTLOOK, UNCERTAINTY IN THE
FORECAST INCREASES AS THE RIDGE STARTS TO BREAK DOWN AND A TROUGH
BEGINS TO DEVELOP ALONG THE WEST COAST. ENSEMBLE MODEL CLUSTER
ANALYSIS SUGGESTS A SPLIT BETWEEN SOLUTIONS THAT BRING SOMETHING
AKIN TO AN INSIDE SLIDER TO THE GREAT BASIN FOR THE UPCOMING WEEKEND
AND THOSE THAT KEEP THE RIDGING IN PLAY. THE INSIDE SLIDER SOLUTION
SLIGHTLY DOMINATES THE CLUSTER SPACE AT THIS TIME, BUT WE WILL WAIT
FOR THE MODEL TREND TO BECOME CLEARER BEFORE COMMITTING TO A
PARTICULAR SOLUTION.
AVIATION
(18Z TAFS)
ISSUED AT 1047 AM PDT MON OCT 5 2026
A SHALLOW MARINE LAYER (AROUND 500 FEET IN DEPTH) HAS RETURNED
ALLOWING FOR COASTAL STRATUS AND FOG TO RETURN TO THE COASTAL
SITES. AS SURFACE TEMPERATURES WARM, EXPECTING MOSTLY VFR
CONDITIONS TO PERSIST THROUGH THE EARLY EVENING BEFORE A RETURN OF
STRATUS AND/OR FOG RETURNS TO COASTAL SITES LATE THIS EVENING AND
INTO TUESDAY MORNING. THE GREATEST POTENTIAL FOR SUB-IFR WILL BE
AT HAF, MRY, AND SNS WITH THE REST OF THE REGION REMAINING VFR
THROUGHOUT THE TAF PERIOD. ONSHORE WINDS WILL INCREASE TODAY AND
BE SLIGHTLY STRONGER THAN PREVIOUS DAYS BEFORE EASING AFTER SUNSET
AND MORE SO INTO TUESDAY MORNING. ANY LOW CEILINGS AND/OR FOG ARE
LIKELY TO DISSIPATE BETWEEN 16Z-17Z TUESDAY.
VICINITY OF SFO...VFR. ONSHORE WINDS WILL INCREASE BY LATE
MORNING AND PERSIST INTO EARLY EVENING BEFORE DIMINISHING. WEST TO
NORTHWEST WINDS WILL BE STRONGEST THIS AFTERNOON THROUGH MID-
EVENING WITH WINDS FORECAST TO BE UP TO 16KT. WHILE THERE IS A LOW
PROBABILITY (GENERALLY 20-25%) OF SUB-MVFR FROM 12Z-17Z TUESDAY,
HAVE THESE OUT OF THE FORECAST AT THIS TIME.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR. ONSHORE WINDS WILL INCREASE THIS
AFTERNOON BEFORE DIMINISHING AFTER SUNSET. SUB-IFR CONDITIONS ARE
FORECAST TO RETURN TO THE REGION LATE THIS EVENING AND PERSIST
INTO TUESDAY MORNING WITH GENERALLY MODERATE TO HIGH CONFIDENCE OF
OCCURRENCE. LOW CEILING AND FOG WILL BEGIN TO DISSIPATE BETWEEN
16Z- 17Z TUESDAY WITH AFTERNOON HEATING.
MARINE
(TODAY THROUGH SATURDAY)
ISSUED AT 930 AM PDT MON OCT 5 2026
AN EXTENSIVE LOW STRATUS AND FOG LAYER IS STEADILY ADVANCING
EASTWARD ACROSS THE COASTAL WATERS AND WILL REACH MUCH OF THE
COASTLINE THROUGHOUT THE MORNING AND INTO THE AFTERNOON. A GENTLE
TO MODERATE BREEZE AND SLIGHT TO MODERATE WAVE HEIGHTS PERSIST
INTO MIDWEEK. WINDS INCREASE AND WAVE HEIGHTS BUILD, SEAS BECOMING
ROUGH ACROSS THE OUTER WATERS, FRIDAY INTO THE WEEKEND.
FIRE WEATHER
ISSUED AT 306 AM PDT MON OCT 5 2026
STRONG RIDGING ALOFT WILL LEAD TO HOT AND DRY CONDITIONS THROUGH
THURSDAY WITH ELEVATED FIRE WEATHER CONDITIONS ACROSS THE HIGHER
ELEVATIONS. POOR TO VERY POOR OVERNIGHT HUMIDITY RECOVERIES WILL
CONTINUE ACROSS THE THERMAL BELTS WITH PUSHES OF OFFSHORE FLOW
EACH MORNING. HAZARDOUS HEAT WILL CONTINUE THROUGH THURSDAY WITH
MAJOR TO EXTREME RISKS OF HEAT-RELATED ILLNESSES ACROSS MOST
MOUNTAIN RANGES. A PATTERN CHANGE LATER THIS WEEK WILL BRING
COOLER CONDITIONS TO THE REGION.
MTR WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY UNTIL 10 PM PDT THURSDAY FOR CAZ503-504-506-508-
510-512>518.
PZ...NONE.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...RGASS
MARINE...RGASS
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