FXUS66 KMTR 281222
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
522 AM PDT Mon Sep 28 2026

...New AVIATION, FIRE WEATHER...

.KEY MESSAGES...
Updated at 1240 AM PDT Mon Sep 28 2026

 - Elevated fire weather conditions across the higher terrain
   through Wednesday

 - Areas of moderate HeatRisk across the interior Wednesday
   through Sunday

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

&&

.SHORT TERM...
Issued at 1240 AM PDT Mon Sep 28 2026
(Monday through Tuesday)

An upper-level low will dig diagonally across the state Monday into 
Tuesday. Sensible weather wise, Monday will be the coolest day of 
the week with temperatures near to slightly below normal alongside 
onshore winds of 10-20 mph with gusts up to 30 mph. All signs point 
to the 2,000 ft marine layer mixing out, yet it prevails. The 
associated lift and accompanying wind from the aforementioned low 
will favor an earlier than normal clearing time of stratus (although 
it's more like stratocumulus out there). Of more impact is the 
northerly/offshore flow that will develop as upper-level ridging 
noses in from the Eastern Pacific Ocean in the low's wake. Wind 
speeds of 15-25 mph with gusts up to 35 mph can be expected across 
the interior higher terrain, especially the North Bay Interior 
Mountains and East Bay Interior Mountains. This will start tonight 
(Sunday night/Monday morning) and peak Monday night/Tuesday morning 
and Tuesday night/Wednesday morning. The combination of dry and 
windy conditions will yield elevated fire weather conditions for the 
higher terrain during this time. Tuesday and Wednesday will be 
warmer and drier from rising heights and northerly (drying) winds. 
Northerly/offshore flow will also minimize if not erode the marine 
layer, allowing the coast to warmup. Minor coastal flooding for
bayshore locations along the San Francisco Bay, San Pablo Bay, and
Monterey Bay during the highest high tide Monday through Thursday.

&&

.LONG TERM...
Issued at 1240 AM PDT Mon Sep 28 2026
(Wednesday through Sunday)

Global ensemble clusters are in agreement that upper-level ridging 
with anomalously high heights will dictate our forecast Wednesday 
through Sunday. 850 mb temperatures above the 90th percentile will 
support temperatures 10 to 15 degrees above normal. As a result, 
areas of moderate HeatRisk are expected across the interior above 
and away from the compressed (<~1,000 ft) marine layer. No daily 
maximum temperature records are in jeopardy.

&&

.AVIATION...
(12Z TAFS)
Issued at 515 AM PDT Mon Sep 28 2026

The marine layer this morning is around 1500-2000ft, as evident by 
the expansive stratus deck across both coastal and interior valley 
locations. Drier air is still anticipated to work its way through 
the region today, which should lead to an earlier clearing of clouds 
this morning. After that, VFR conditions are expected to prevail 
with with onshore flow gradually becoming onshore. 

Vicinity of SFO...Stratus and MVFR cigs are being observed this 
morning, with hi-res models showing clearing between 13-17Z. Once 
clear, VFR conditions should prevail and be accompanied with onshore 
flow. Models show another breezy afternoon and evening around SFO, 
with gusts up to 20-25kt from roughly 20-06Z. Onshore winds of less 
than 10kt are expected through the rest of the TAF cycle. 

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...The forecast looks to be on track this 
morning, with MVFR cigs holding around the region. Stratus should 
begin clearing the region between 16-18Z, which should lead to a 
stretch of VFR conditions. Opted to trend with a more optimistic 
forecast for the evening, as hi-res models over the last few runs 
have eased on the return of stratus tonight. Will need to keep an 
eye on it and see how the forecast pans out and if we're able to get 
any clouds as the marine layer settles to 500ft. 

&&

.MARINE...
(Today through Saturday)
Issued at 252 AM PDT Mon Sep 28 2026

Moderate to strong north winds will continue through Wednesday
with the strongest gusts across the northern outer waters and
south of Point Pinos, where near gale force gusts are expected at
times. Rough seas will build in response to these winds and will
subside to moderate by the end of the week due to northerly winds
becoming light to moderate. Tropical activity will produce long
period swell up to 16 seconds Wednesday and Thursday.

&&

.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 from 11 AM this morning to 5 PM PDT 
     Thursday for CAZ006-506-508-529-530.

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

     Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this 
     evening for Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory until 11 PM PDT this evening for Pt Pinos 
     to Pt Piedras Blancas 0-10 nm.

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

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...KR
MARINE...KR

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Prepared by Boulder-Creek.com Weather at: Mon Sep 28 06:30:03 PDT 2026