FXUS66 KMTR 030744
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1244 AM PDT Sat Oct 3 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 1243 AM PDT Sat Oct 3 2026

 - Moderate to major HeatRisk across the Bay Area and Central
   Coast Saturday and Sunday

 - Moderate to major HeatRisk across the interior Bay Area and 
   Central Coast Monday through Thursday

 - Elevated fire weather conditions across the higher terrain
   through Thursday

&&

.SHORT TERM...
Issued at 1243 AM PDT Sat Oct 3 2026
(Saturday and Sunday)

The 00Z sounding observed an 850 mb temperature of 22.95 degrees 
Celsius and a 500 mb height of 5900 meters, both of these are above 
the 90th percentile. The heat will peak this weekend as an upper-
level longwave ridge drifts in from the Eastern Pacific Ocean. A 
Heat Advisory will go into effect at 11 AM Saturday and run through 
10 PM Sunday for most of the Bay Area and Central Coast. It was 
extended in area to include the Carmel Valley, Hollister Valley, 
Marin Coastal Range, Northern Monterey Bay, Northern Salinas Valley, 
and San Francisco. Now, the only places that are not included is the 
North Bay Coast, San Francisco Peninsula Coast, and Southern 
Monterey Bay; this is banking on a compressed marine layer keeping 
these spots cool. If the compressed marine layer is able to survive, 
expect reduced visibility from fog along the coast. If it is not 
able to survive, coastal conditions will be hotter than currently 
forecast. Moderate to major HeatRisk will result from maximum 
temperatures 10 to 20 degrees above normal. Minimum temperatures 10 
to 20 degrees above normal with weaker than normal onshore flow will 
bring limited relief overnight, also contributing to HeatRisk. Even 
less relief is expected in the higher terrain where elevated fire 
weather conditions continue with hot and dry conditions, prominent 
thermal belting, and prolonged burn periods.

&&

.LONG TERM...
Issued at 1243 AM PDT Sat Oct 3 2026
(Monday through Friday)

The Heat Advisory will remain in effect through 10 PM Monday for the 
interior Bay Area and Central Coast. Upper-level shortwave troughing 
will undercut the ridge and bring an increase in onshore flow 
Monday; however, the interior will remain hot. Global ensemble 
clusters are in agreement that heights will rebuild Tuesday and peak 
Wednesday. With little change in the day-to-day forecast and the 
cumulative heat impacts, we could be looking at an extended Heat 
Advisory. This is especially true for the East Bay and South Bay 
where major HeatRisk is likely (60%+) through Wednesday. The marine 
layer will remain compressed during this time, keeping the coast 
cool and likely reducing visibility from fog. Elevated fire weather 
conditions will continue in the higher terrain through Thursday for 
hot and dry conditions with prominent thermal belting and prolonged 
burn periods. Thursday remains uncertain on ridge vs. trough, but by 
Friday it is likely that heights will begin to fall.

&&

.AVIATION...
(06Z TAFS)
Issued at 1002 PM PDT Fri Oct 2 2026

VFR through the TAF period at most terminals with coastal sites 
having a higher chance of brief LIFR ceilings overnight. VFR 
conditions prevail across the region by Saturday morning with a 
lower chance for stratus to return tomorrow evening as the marine 
layer becomes more shallow. Medium confidence on the exact timing 
of LIFR ceilings at HAF and Monterey Bay terminals. Reductions to 
visibility are still possible at these sites, though confidence has 
decreased on the exact impacts and timing. Light onshore winds 
continue through the night, occasionally becoming variable due to a 
weak push of offshore flow. By Saturday afternoon, moderate onshore 
breezes around 7 to 12 kt prevail.

Vicinity of SFO...VFR through the TAF cycle. High clouds will 
continue to pass through the overnight hours. A brief bay breeze 
will settle in at SFO Saturday morning before shifting to its usual 
northwesterly flow with clear skies.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR with light winds shifting between a 
northwest to easterly flow. Overnight, east to southeasterly breezes 
prevail with medium confidence on the arrival of LIFR ceilings. 
Looking at current satellite imagery (as of 10PM PDT), dry air is 
impacting the robustness of the marine stratus deck. If LIFR 
ceilings develop, they will be short-lived. Low to medium confidence 
on fog development at MRY. By Saturday morning, clear skies prevail 
as onshore winds increase to 5 to 10 kt. 

&&

.MARINE...
(Tonight through next Thursday)
Issued at 1002 PM PDT Fri Oct 2 2026

North to northwesterly breezes remain gentle to moderate into
early  week, allowing for slight to moderate seas to persist.

&&

.FIRE WEATHER...
Issued at 353 AM PDT Fri Oct 2 2026

Ridging will lead to hot and dry conditions across the region 
through the seven day outlook. Daytime humidity retention will 
remain poor to very poor away from the immediate coast, while 
overnight, the thermal belts remain active and humidity retention 
in the higher elevations is poor. Pushes of offshore flow are 
possible in the higher elevations each morning. Hazardous heat 
builds this weekend, particularly impacting fire crews across the 
interior mountains and the Santa Lucia range.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory from 11 AM this morning to 10 PM PDT Sunday for 
     CAZ006-502-528-529.

     Heat Advisory from 11 AM this morning to 10 PM PDT Monday for 
     CAZ503-504-506-508-510-512>518.

PZ...None.
&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...Navarrete
MARINE...Navarrete

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Prepared by Boulder-Creek.com Weather at: Sat Oct 3 04:30:03 PDT 2026