FXUS66 KMTR 020738
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1238 AM PDT Fri Oct 2 2026

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

.KEY MESSAGES...
Updated at 1237 AM PDT Fri Oct 2 2026

 - Moderate to major HeatRisk across the interior through Thursday

 - Elevated fire weather conditions across the higher terrain
   through Thursday

 - Minor coastal flooding for bayshore locations along the San 
   Francisco Bay, San Pablo Bay, and Monterey Bay Friday

&&

.SHORT TERM...
Issued at 1237 AM PDT Fri Oct 2 2026
(Today and tonight)

The 00Z sounding observed an 850 mb temperature of 21.75 degrees 
Celsius and a 500 mb height of 5900 meters; both of these are above 
the 90th percentile of 20.6 degrees Celsius and 5883 meters, 
respectively. Upper-level ridging across the Southwest will bring 
temperatures 10 to 15 degrees above normal to the interior Friday, 
resulting in areas of moderate HeatRisk. Subsidence aloft will 
compress the marine layer, keeping it confined to the coast and 
supporting fog development. Above the marine layer in the higher 
terrain, elevated fire weather conditions continue from hot and dry 
conditions with offshore flow overnight. Minor coastal flooding for 
bayshore locations along the San Francisco Bay, San Pablo Bay, and 
Monterey Bay will occur during high tide Friday afternoon.

&&

.LONG TERM...
Issued at 1237 AM PDT Fri Oct 2 2026
(Saturday through Thursday)

A Heat Advisory is in effect for most of the interior from 11AM 
Saturday through 10PM Sunday. This covers the peak of the heat as 
upper-level longwave ridging drifts in from the Eastern Pacific 
Ocean. A compressed marine layer around 500 feet is currently 
forecast during this time; however, if it erodes from offshore flow 
or clouds fail to develop, the coast will be hotter than forecast. 
Upper-level shortwave troughing will undercut the ridge Sunday into 
Monday with the ridge rebounding across the West Coast Tuesday into 
Wednesday. No matter how you slice it, it is going to be hot for the 
next week with temperatures 15 to 20 degrees above normal and 
moderate to major HeatRisk across the interior. A compressed marine 
layer, weaker than normal onshore flow, and minimum temperatures 
well above normal will bring less relief than normal overnight. This 
will also keep elevated fire weather conditions across the higher 
terrain. Even though we are nearing the end of our heat season, 
cumulative heat impacts are expected across the interior. With all 
that being said, no records are in jeopardy as October is one of the 
hottest months for the region. Finally by Thursday, 44% of global 
ensemble clusters begin to show signs of a pattern change via 
falling heights.

&&

.AVIATION...
(06Z TAFS)
Issued at 929 PM PDT Thu Oct 1 2026

The stratus is rolling in, bringing IFR to LIFR conditions to the
coastal terminals. These clouds will continue to push inland
through the night, impacting all but the most inland terminals.
Clearing times will be similar to Thursday morning, roughly
17-18Z.

Vicinity of SFO...High clouds are obscuring the current extent of
the stratus on the satellite image, but Half Moon Bay is reporting
300 foot ceilings for what it's worth. The probability of IFR
ceilings reaching SFO has increased to 50-70 percent with the best
window between 12Z and 15Z. If these ceilings do reach the
terminal, they should quickly clear through the late morning.

SFO Bridge Approach...This is the type of shallow marine layer set
up where the approach could get ceilings a couple hours earlier 
than the terminal as the stratus moves in through the Golden Gate 
and swirls around the SF Bay before reaching SFO.

Monterey Bay Terminals...IFR-LIFR ceilings are firmly in place at
both SNS and MRY and are very unlikely to improve over the next 12
hours. In fact there is a decent chance for fog at both terminals
through the early morning. 

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 929 PM PDT Thu Oct 1 2026

A gentle to moderate northerly breeze will continue through the
weekend and into next week.

&&

.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 this evening 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...Sarment
LONG TERM....Sarment
AVIATION...Flynn
MARINE...Flynn

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Prepared by Boulder-Creek.com Weather at: Fri Oct 2 02:30:03 PDT 2026