FXUS66 KMTR 261904
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1204 PM PDT Sat Sep 26 2026

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

.KEY MESSAGES...
Updated at 1204 PM PDT Sat Sep 26 2026

 - Cooler conditions through Sunday

 - Warmer temperatures return Tuesday through the next week

&&

.SHORT TERM...
Issued at 1204 PM PDT Sat Sep 26 2026
(This evening through Sunday night)

The stratus deck has mixed out to the immediate coast of Marin 
County and the Ocean Beach side of San Francisco and lurking near or 
just off the coast of San Mateo County. High clouds continue to flow 
over the North Bay and will continue to do so through the day, as 
the stratus deck returns to many of the coastal valleys this evening 
into the overnight period. 

A developing trough with an axis around 600 miles west of Cape 
Mendocino is approaching the West Coast, digging deeper into the 
upper level flow as it does so and eventually dropping deep enough 
to cross into the California coast, where it should further develop 
into a cut-off low somewhere around the North Coast and the northern 
half of the Central Valley through the latter portion of Sunday. The 
influence of the cut-off low will bring cooler and more moist 
conditions to the region. High temperatures will range around 5 to 
15 degrees below seasonal averages for today and Sunday, with highs 
in the inland valleys reaching the middle 70s to lower 80s today and 
the 70s on Sunday. High temperatures in the warmest portions of 
southern Monterey County will range from the middle 80s to lower 90s 
today, and the upper 70s to middle 80s on Sunday. Meanwhile, the 
Bayshore regions should expect highs in the upper 60s to upper 70s 
on Saturday and the middle 60s to middle 70s on Sunday, while the 
Pacific coast remains relatively cool with highs in the upper 50s to 
middle 60s on both days. 

As the cut-off low moves across the state through the weekend, 
cooler temperatures and some incoming moisture should result in a 
wetter mid-layer, around the 300-500 mb layer. Exceedingly dry lower 
layers should cause the evaporation of most precipitation that may 
result, but can't rule out a few sprinkles overnight for the coastal 
regions and the highest peaks. 

&&

.LONG TERM...
Issued at 1204 PM PDT Sat Sep 26 2026
(Monday through next Friday)

Ridging should return to the region on Monday as the low moves into 
the Mojave Desert, setting up pushes of higher elevation offshore 
flow each morning from Monday to Wednesday, chiefly across the North 
and East Bay interior mountains. The strongest push looks to be on 
Tuesday morning with wind gusts of 25 to 35 mph possible in the 
interior mountains of the North Bay. The potential for wind gusts 
above 35 mph is greatest at the ridgeline of the Vaca Mountains 
along the eastern border of Napa County. 

Otherwise, the arrival of the ridge should allow for temperatures to 
warm for the next week. By Tuesday, highs should reach the middle 
80s to middle 90s in the inland valleys, the middle 70s to the 
middle 80s for the Bayshore regions, and the 60s to the lower 70s 
for the Pacific coast. These highs should basically remain stable 
through the rest of the 7-day outlook as ensemble model means and 
cluster guidance suggest that the ridging pattern should stick 
around in some shape or form into the upcoming weekend and possibly 
beyond.

&&

.AVIATION...
(18Z TAFS)
Issued at 1046 AM PDT Sat Sep 26 2026

Stratus is clearing rapidly across affected area terminal at this
hour. VFR conditions expected prevail through this afternoon with
a return of low clouds expected this evening over coastal
terminals (KMRY and KHAF) and after midnight/early Sunday morning
over inland terminals. 

A short wave trough approaching the region tonight into Sunday 
will deepens the marine layer overnight. This may result in light
rain or drizzle especially along the coast. However the 
relatively dry boundary layer may not allow it to reach the ground
and may result in virga.

Vicinity of SFO...VFR conditions with scattered high clouds will 
prevail through the remainder of the day with moderate confidence 
that MVFR cigs will return overnight. Lighter winds than yesterday
are anticipated. An approaching short wave trough will deepens 
the marine layer overnight resulting in the possibility of wet 
runways by morning due to light rain or drizzle. 

SFO Bridge Approach...Similar to KSFO. 

Monterey Bay Terminals...VFR conditions will prevail through the 
remainder of the day with moderately high confidence that MVFR 
cigs will return this evening. Light to locally moderate onshore
flow is anticipated. An approaching short wave trough will 
deepens the marine layer overnight resulting in the possibility 
of wet runways by morning due to light rain or drizzle.

&&

.MARINE...
(Today through Thursday)
Issued at 907 AM PDT Sat Sep 26 2026

Moderate north winds will persist through the remainder of the
weekend increasing Sunday night into Monday becoming strong and
gusty as a ridge of high pressure begins building in over the 
EPAC tightening the pressure gradient across the coastal waters. 
Strongest winds will be over the outer coastal waters accompanies
by hazardous boating conditions.

&&

.FIRE WEATHER...
Issued at 420 AM PDT Sat Sep 26 2026

Our diffuse cold front continues to slowly move southward through
Southern California. In its wake, some areas have benefited from 
the cooler and slightly more "moist" conditions this morning. The
exception, however, is across the higher terrain of the Santa 
Cruz Mountains as well as the Santa Lucia and Diablo Ranges where 
RH recovery remains poor (20-40%). Afternoon humidity will remain
under 40%, largely for areas away from the coast. A push of 
onshore flow is expected later this evening into Sunday morning 
resulting in the marine layer deepening to around 2,000 feet ahead
of an upper trough. This moisture push should diminish the areal 
coverage of poor RH recovery Sunday and Monday morning. A few 
sprinkles cannot be ruled out along the highest peaks associated 
with this upper low Sunday AM. Dry and modest offshore breezes 
will be a possibility Tuesday and into Wednesday, with the 
potential for wind gusts above 35 mph being greatest across the 
higher terrain of the North Bay in the wake of this upper low. 
Farther south across the Central Coast, the primary impact from 
this low will be a return to widespread poor RH recovery with some
locales across the Santa Lucia Range struggling to see max RH 
above 30% Wednesday morning. 

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Monday for Pt Pinos to Pt 
     Piedras Blancas 0-10 nm.

     Small Craft Advisory until 9 AM PDT Monday for Pt Arena to Pt 
     Reyes 10-60 NM.

     Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt 
     to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...CW
MARINE...CW

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Prepared by Boulder-Creek.com Weather at: Sat Sep 26 14:30:03 PDT 2026