821
FXUS66 KMTR 291739
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1039 AM PDT Tue Sep 29 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 135 AM PDT Tue Sep 29 2026

 - Elevated fire weather conditions across the higher terrain
   through Wednesday

 - Areas of moderate HeatRisk across the interior Wednesday
   through Monday

 - Minor coastal flooding for bayshore locations along the San Francisco,
   San Pablo, and Monterey Bays Monday through Thursday

&&

.SHORT TERM...
Issued at 135 AM PDT Tue Sep 29 2026
(Today and Wednesday)

The warming and drying trend kicks off today as upper-level ridging
noses in from the Eastern Pacific Ocean behind the departing upper-
level low. This pattern will tighten and support a
northerly/offshore pressure gradient that will bring elevated fire
weather conditions to the higher terrain through Wednesday.
Northerly/Offshore flow will be strongest overnight and in the
higher terrain with speeds of 15-25 mph and gusts up to 35 mph.
Sensible weather wise, temperatures will be near to 10 degrees above
normal with areas of moderate HeatRisk. If the marine layer is able
to survive, expect it to remain confined to the immediate coast and
result in reduced visibility. Minor coastal flooding will continue
during the highest high tide through Thursday for bayshore locations
along the San Francisco Bay, San Pablo Bay, and Monterey Bay.

&&

.LONG TERM...
Issued at 135 AM PDT Tue Sep 29 2026
(Thursday through Monday)

Global ensemble clusters are in relatively good agreement that
anomalously high heights will persist through Monday. The heat peaks
over the weekend as upper-level longwave ridging moves in from the
Eastern Pacific Ocean. Still, temperatures will remain 10 to 15
degrees above normal with moderate HeatRisk away from the compressed
marine layer at the coast. No records are in jeopardy.

&&

.AVIATION...
(18Z TAFS)
Issued at 1033 AM PDT Tue Sep 29 2026

Most terminals were VFR this morning under clear skies, but
Monterey Bay region and N Bay Valleys had dense fog leading to
LIFR conditions. Since then, VFR have developed and will continue
through this afternoon. Gusty onshore winds possible for SFO and
OAK this afternoon. For tonight another night of mostly VFR most
terminals. However, a shallow/compressed marine layer will allow
for periods of LIFR conditions - same locations N Bay and
Monterey Bay region. Conf is 30% for dense fog. Conditions may
ebb and flow so included dense fog as tempo group.

Vicinity of SFO...VFR. Gusty onshore this afternoon up to 20 kt.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR this afternoon. Lower CIGs return
tonight with LIFR conditions possible tomorrow AM due to dense
fog.

&&

.MARINE...
(Today through Sunday)
Issued at 1033 AM PDT Tue Sep 29 2026

Strong high pressure off the California Coast will result in fresh
to near gale northerly breezes through Wednesday over the coastal
waters. Frequent gale force gusts are expected across the
northern waters through Wednesday morning. Conditions will begin
to improve Wednesday night as northerly breezes diminish to become
gentle to moderate, with locally hazardous conditions across the
northern outer waters likely to continue. Rough to very rough seas
through Wednesday will subside to become moderate to rough.

&&

.FIRE WEATHER...
Issued at 515 AM PDT Mon Sep 28 2026

The marine layer persists this morning, around 1500-2000ft, but
should gradually compress to around 500ft throughout the day.
Today will be coolest day of the week, though it is also the start
of a warming trend. Offshore flow gradually works its way into the
region today, which will lead to breezy winds each morning from through
Wednesday. The strongest winds are expected on Tuesday morning in
the interior mountains of the North and East Bays, where wind
gusts could reach 30-35 mph. These offshore winds should
contribute to poor overnight humidity recoveries, with overnight
relative humidities as low as 20-40% above the marine layer.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 5 PM PDT Thursday for CAZ006-506-
     508-529-530.

PZ...Small Craft Advisory until 3 PM PDT this afternoon for Pt Arena
     to Pt Reyes 0-10 nm.

     Gale Warning from 3 PM this afternoon to 9 PM PDT this evening
     for Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 AM PDT Wednesday for Pigeon Pt to
     Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt
     Reyes to Pigeon Pt 0-10 nm.

     Gale Warning until 9 AM PDT Wednesday for Pt Arena to Pt Reyes
     10-60 NM.

     Small Craft Advisory until 3 PM PDT Wednesday for Pigeon Pt to
     Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...MM
MARINE...MM

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