562
FXUS66 KMTR 041502
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
802 AM PDT Sat Oct 4 2025

...New UPDATE...

.KEY MESSAGES...
Updated at 1245 AM PDT Sat Oct 4 2025

 - Warmer and drier conditions through mid week.

 - Next chance for rain late next week.

&&

.UPDATE...
Issued at 802 AM PDT Sat Oct 4 2025

Weak offshore winds have developed over the higher terrain this
morning, however onshore winds are forecast to prevail this
afternoon in the lower elevations. Stratus remains over the San
Mateo County coastline, southward around the Monterey Bay Region,
into the Hollister Valley, and the southern Salinas Valley. These
clouds will dissipate through the remainder of the morning as
offshore flow persist aloft. Thus, temperatures will warm up into
the mid to upper 60s near the coast and mid to upper 70s inland.
These values remain near to slightly below seasonal averages. The
ongoing forecast remains on track this morning with no updates
anticipated.

RGass

&&

.SHORT TERM...
Issued at 1245 AM PDT Sat Oct 4 2025
(Today and tonight)

The 500 mb low has moved into Nevada and will continue NE while
being absorbed back into the long wave pattern over the next 24
hours. Meanwhile a surface low pressure trough will develop over
California. The gradient between this low pressure and building
high pressure over the subtropical Eastern Pacific will support
moderate N-NW winds along the coast and NW-SE oriented valleys.
The marine layer will gradually recover today as warmer, drier
air moves over the stable pool of cool air near the surface.
Temperatures will be near seasonal normal with mid to upper 70s
inland and mid to upper 60s along the coast. Overall a pretty nice
Saturday.

&&

.LONG TERM...
Issued at 1245 AM PDT Sat Oct 4 2025
(Sunday through Friday)

The trough over California will gradually shift towards the coast
starting Sunday, nudged by weak upper level troughing. The upper
level trough will evolve into a cut-off low off the Central Coast
by Sunday, further pushing the surface trough to the coast or even
offshore. As the surface trough shifts further west, high pressure
will build over the northern Rockies. This set up will support
down-gradient, offshore N or NE winds. These winds will bring a
warmer, drier air mass to the Bay Area from Sunday through mid
week. The 500 mb height will remain below the median for this
time of year (5800 m) which will moderate the temperatures and
should allow a 1,000-1,500 ft marine layer to survive under the
offshore winds. The skies will be clear in the afternoon, but
morning clouds are still expected in the typical marine layer
locations this week. While the minimum humidity will drop below
30% across the North Bay interior mountains, the mild
temperatures, moderate wind speed, and higher than normal fuel
moisture will limit fire weather concerns.

The offshore winds will die down by Friday as a new, deep low
pressure system approaches the west coast and becomes the dominant
feature. This system will bring a cold front through the Bay Area
next weekend, with some rain likely. The ensembles have backed
off on the amount, however. There is now a 10-30% chance of
receiving more than 1" of rain across the North Bay, with less
than 10% of reaching that threshold across the rest of the cwa.
The disturbed weather looks to last for several days, with
stratiform rain ahead of the front, and showers after it moves
through.

&&

.AVIATION...
(12Z TAFS)
Issued at 357 AM PDT Sat Oct 4 2025

Shallow marine stratus returning to coastal areas and coast-
adjacent valleys through this morning. Patchy stratus coverage
around the Bay Area leads to some uncertainty regarding coverage
at terminals around sunrise. Slight chance of IFR/MVFR cigs
through sunrise for North Bay and Bay Area terminals north of
KSJC, but shouldn`t be persistent enough for prevailing. Thus,
kept TEMPO group in TAFs. Beyond this morning, VFR through the
rest of the period with stratus returning along the immediate
coast.

Vicinity of SFO...Currently looking at marine stratus invof KOAK
and KHAF, but not quite solid coverage across the Bay. Slight
chance of MVFR cigs affecting the terminal through sunrise, but
hedging toward the lower end of impacts (if any) based on the
pattern. Beyond this morning, VFR through the period.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR cigs lingering through sunrise, then
VFR thereafter. Marine stratus will likely linger along coastal
areas along the southern portion of the bay through today. A bit
more uncertainty surrounding the coverage overnight tonight.
Timing of stratus return in TAFs is reasonably confident, but not
as confident on SCT vs. BKN from late this evening onward into
Sunday morning.

&&

.MARINE...
(Today through Thursday)
Issued at 357 AM PDT Sat Oct 4 2025

Fresh breeze across the waters, subsiding through the weekend.
This will translate to steep and rough seas up to 10 feet
resulting in hazardous boating conditions. Winds continue to ease
into next week with light winds persisting across the waters
through the work week.

&&

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

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

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

     Small Craft Advisory until 9 AM PDT Sunday for Pigeon Pt to Pt
     Pinos 10-60 NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Behringer
MARINE...Behringer

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, X, and YouTube at:
www.facebook.com/nwsbayarea
x.com/nwsbayarea
www.youtube.com/nwsbayarea