285
FXUS66 KMTR 090847
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1247 AM PST Sun Nov 9 2025

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

.KEY MESSAGES...
Updated at 1247 AM PST Sun Nov 9 2025

 - Warming and drying trend through Monday

 - Unsettled weather pattern returns middle of next week

&&

.SHORT TERM...
Issued at 1247 AM PST Sun Nov 9 2025
(Today and tonight)

Mostly clear conditions continue overnight with large scale offshore
flow keeping the lower atmosphere relatively dry, although some
stratus and fog development is possible in the North Bay valleys and
far eastern Contra Costa county. Low temperatures tonight range from
near 50 within wind-sheltered valleys, to the middle 50s for the
rest of the lower elevations and the upper 50s to lower 60s along
the thermal belts. The weather pattern today should continue to be
warm, clear, and dry underneath a large scale ridge, with highs
reaching 10 to 20 degrees above seasonal averages away from the
immediate coastal area. High temperatures are forecast around the
lower to middle 80s in the inland valleys, except in the Morgan Hill-
Hollister corridor and the southern Salinas Valley where
temperatures reach the upper 80s to near 90, while the bays see
highs in the upper 70s to lower 80s and the Pacific coast reaches
the upper 60s to lower 70s. Although this is a lower confidence
outcome (around a 10-20% probability), there is some scope for
significantly warmer temperatures on the western side of the coastal
ranges and the Berkeley-San Leandro hills, particularly if stronger
offshore flow develops than the current forecast. In the event that
these scenarios develop, the 75th percentile high temperatures (25%
chance of warmer temperatures) remain a degree or two above the
current forecast for the immediate San Francisco Bay region, while
the 90th percentile (10% chance of warmer temperatures) jump into
the middle to upper 80s.

&&

.LONG TERM...
Issued at 1247 AM PST Sun Nov 9 2025
(Monday through Saturday)

The ridge remains established through Monday, when highs similar to
or a couple degrees above today`s forecast are expected, with similar
caveats if offshore flow comes in stronger than the current
forecast. Overnight, the thermal belts remain active through Tuesday
morning, resulting in mild overnight lows and offshore winds across
the higher terrain.

On Tuesday, the ridge begins to erode and shuffle to the east,
starting a cooling trend that will bring highs down around 2 to 5
degrees across the region, with the most pronounced cooling at the
coastal areas. By Wednesday, the decaying ridge should allow a deep
trough developing across the eastern Pacific to enter the West Coast
and bring a period of unsettled weather to the region. In terms of
this particular trough, the unsettled regime comes in two parts.
First, the most intense rain band comes through the region late on
Wednesday into Thursday. This does bring in widespread rainfall
across the Bay Area and Central Coast, but the exact totals, and
thus downstream effects on flooding and landslide risk, are still in
question. For the period from 4 AM Wednesday to 4 AM Friday, the NBM
gives the following ranges for 25th to 75th percentile rainfall
totals (that is, a 50% probability that the eventual rainfall falls
within this range): 1.0"-1.9" at Sonoma County Airport and San
Francisco International Airport, 0.8"-1.5" at San Jose Airport, and
1"-1.7" at the Livermore Airport and Monterey Regional Airport. The
NBM is also keeping a 10-20% probability of thunderstorms across the
Bay Area and Central Coast Wednesday night into Thursday, and the
ECMWF is forecasting K-Index values up to 30-35 degrees Celsius,
suggesting that scattered thunderstorms are possible.

After the main rain band moves out late Thursday, an extended period
of lighter rain, possibly showery in nature, lingers Friday into the
upcoming weekend. The axis of the upper level trough crosses into
the state early on Friday, promoting unstable conditions resulting
in the possible development of convectively driven showers. There is
also a chance that a cut-off low could develop off the coast of
southern California, which could enhance the rain potential across
the Central Coast. That said, with the moisture tap moving to the
south and into southern California and Baja California, there will
be less moisture for the showers to tap into, and the rain totals
for this part of the system trend lower than those on Wednesday and
Thursday. The precipitation chances start out around 40-60% on
Friday morning and steadily decrease into Saturday.

Beyond the 7 day outlook, ensemble model means are suggesting
another trough may develop somewhere around the Day 8-9 (the 16th
and 17th) timeframe, bringing another chance of rain to the region.
This far out, attempting to tease out any further details is a
fool`s errand.

&&

.AVIATION...
(06Z TAFS)
Issued at 926 PM PST Sat Nov 8 2025

VFR conditions and light to moderate winds expected to persist at
the majority of terminals through the TAF period. The exception is
STS, where mist is already moving up the Russian River drainage
and impacting the terminal. This will likely persist through most
of Sunday morning before mixing out. A southerly surge is likely
to develop Sunday, but most model guidance keeps the impacts over
the water.

Vicinity of SFO...No major concerns tonight. The current
conditions are warmer and drier than this time yesterday (RH 67%
vs 87%). This should help alleviate any fog concerns like we saw
this morning. Otherwise winds will be light and variable through
the night before a gentle sea breeze develops Sunday afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR conditions expected through the
night with light drainage flow. If any terminals are impacted by
the southerly surge, it will be MRY and SNS late in the TAF
period.

&&

.MARINE...
(Tonight through next Friday)
Issued at 900 PM PST Sat Nov 8 2025

Favorable conditions in the short term with rough conditions later
this week. A gentle to moderate northerly breeze and moderate NW
swell will continue through Tuesday. Late Wednesday winds will
flip to southerly and increase to a strong breeze across the
coastal waters. Winds will remain moderate to strong and gradually
veer back to NW through the day Thursday. These winds, combined
with a building NW swell, will generate rough waves. While the
winds decrease Friday, the high swell continues to build with
significant wave heights reaching up to 15 feet before
diminishing through the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Flynn
MARINE...Flynn

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