FXUS66 KMTR 070713
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1213 AM PDT Fri Aug 7 2026

...New SHORT TERM, LONG TERM, FIRE WEATHER...

.KEY MESSAGES...
Updated at 1211 AM PDT Fri Aug 7 2026

 - Warming trend through the weekend will result in moderate to
   major HeatRisk for the interior

 - Near-critical fire weather conditions in the higher terrain 
   through Sunday

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

&&

.SHORT TERM...
Issued at 1211 AM PDT Fri Aug 7 2026
(Friday through Sunday)

Upper-level ridging across the Four Corners will expand westward 
Friday. Areas of moderate HeatRisk across the interior on Friday 
will expand to become widespread on Saturday and Sunday with areas 
of major HeatRisk. Saturday and Sunday will be the hottest days of 
the week with temperatures 10-15 degrees above normal. Subsidence 
aloft will compress the 1,000 foot marine layer, keeping relief 
confined to the immediate coast. Near-critical fire weather 
conditions persist through the weekend across the interior due to 
very hot and dry conditions. Minor coastal flooding is expected 
during the highest high tide (evening/overnight) for bayshore 
locations along the San Francisco Bay, San Pablo Bay, and Monterey 
Bay Friday evening through Thursday morning. The Pacific Coast may 
need to be added Sunday through Tuesday, it will depend on how the 
positive anomaly performs leading up to it.

&&

.LONG TERM...
Issued at 1211 AM PDT Fri Aug 7 2026
(Monday through Thursday)

Global ensemble clusters are in agreement that upper-level shortwave 
troughing will develop Monday off the West Coast between subtropical 
high pressure across the Eastern Pacific Ocean and the Four Corners 
high. This will result in temperatures moderating to near normal and 
the return of a marine layer around 1,000 feet. The surface pressure 
gradient will support northerly winds across the waters that will be 
hazardous to small craft.

&&

.AVIATION...
(06Z TAFS)
Issued at 1000 PM PDT Thu Aug 6 2026

MVFR-IFR stratus is beginning to expand as it flows into the 
Petaluma Gap and starts edging into the Golden Gate. Stratus 
continues to expand across the coastal valleys through the night 
with low to moderate confidence that impacts extend into the 
interior East Bay. That may depend on exactly how deep the marine 
layer is. So far stratus has been developing later than the earlier 
forecast suggested and the TAFs have been updated to reflect later 
development times. Stratus is expected to mix out back to the 
immediate coastline Friday morning with the breezy onshore winds 
expected to resume in the afternoon. Some stratus expansion is 
possible Friday evening, but most coverage develops after the end of 
the 24-hour TAF period. 

The SJC ASOS will be offline within a window from 07-13Z due to 
maintenance at the station; the TAF is marked AMD NOT SKED as a 
result.

Vicinity of SFO... Low-end MVFR stratus comes into the terminal area 
within the next couple of hours, with lower confidence on timing as 
the high resolution models start with the terminal on the edge of 
the stratus deck. Stratus will gradually mix out through Friday 
morning followed by breezy and possibly gusty northwest winds in the 
afternoon and evening hours. Low to moderate confidence of stratus 
over the terminal Friday night with high resolution models trending 
towards pulling the stratus deck to the north.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... Low confidence in the timing of the 
stratus development at the terminals as observed stratus coverage is 
much lower than model output. Nevertheless high confidence that IFR 
stratus will build over the terminals through the night. Stratus 
will retreat to the coast late Friday morning with gentle northwest 
winds developing in the afternoon hours, diminishing in the evening 
as the stratus returns.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 1000 PM PDT Thu Aug 6 2026

Northwest gentle winds gradually increase to a fresh to strong
breeze, particularly across the outer northern waters on  Saturday
through the middle of the week. Moderate northwest seas  also
build to rough by Sunday morning continuing into the early  part
of next week. Winds and seas remain elevated through the  middle
of next week. A long period southerly swell of 15 to 17  seconds
will impact the coastal waters beginning Saturday  morning.

&&

.FIRE WEATHER...
Issued at 1211 AM PDT Fri Aug 7 2026

Near-critical fire weather conditions persist through the weekend 
across the interior due to very hot and dry conditions. Strong 
thermal belting, extended burn periods, elevated PIG, and near or 
record BI/ERC values are expected. Temperatures will be 10 to 15 
degrees above normal with a compressed marine layer. Poor minimum 
daytime relative humidity as low as 10% in the afternoons with 
little-to-no recovery overnight is expected with nocturnal drying in 
the highest terrain. Even with critically dry conditions, wind is 
the limiting factor preventing this from being a Fire Weather 
Watch/Red Flag Warning event. Outside of the diurnal sea breeze that 
will bring breezy conditions in the afternoons and evenings through 
gaps and passes, onshore flow will be light. Additionally, critical 
conditions are not expected to meet coverage or duration 
requirements to warrant a product.

Sarment

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory from 5 PM this afternoon to 2 AM PDT 
     Thursday for CAZ006-506-508-529-530.

     Heat Advisory from 10 AM Saturday to 10 PM PDT Sunday for CAZ503-
     504-510-512>515-517-518.

PZ...None.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...DialH
MARINE...DialH

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Prepared by Boulder-Creek.com Weather at: Fri Aug 7 04:30:03 PDT 2026