FXUS66 KMTR 250708
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1208 AM PDT Sun Oct 25 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1207 AM PDT Sun Oct 25 2026
- Seasonably warm conditions today
- Cool conditions through the next week
- Rain chances late week into the upcoming weekend
- Minor coastal flooding at high tide for Bayshore locations
through the week
&&
.SHORT TERM...
Issued at 1207 AM PDT Sun Oct 25 2026
(Today and tonight)
Satellite imagery reveals mostly clear skies across the region save
for a patch of stratus that has developed near Bodega Bay and Dillon
Beach and a little bit eastward through the Petaluma Gap. Skies
should remain mostly clear through the next day, barring any
radiational stratus and fog that develops within the North Bay
early in the morning, which should dissipate after sunrise.
A warm period continues across the region as a shortwave ridge
sandwiched between a departing low moving into the Desert Southwest
and an developing one off the coast of British Columbia and the
Pacific Northwest. Highs remain seasonably warm with highs in the
lower to middle 70s expected across the inland valleys, highs in
the upper 70s across the warmest spots of the southern Salinas
Valley and the Morgan Hill-Gilroy area, the upper 60s to lower 70s
close to the Bays, and the upper 50s to middle 60s along the Pacific
coast. A gentle onshore breeze should develop in the afternoon, with
gusts to 20 mph possible within the Salinas Valley.
A combination of high astronomical tides and surge from thermal
expansion effects brings the risk of minor coastal flooding across
Bayshore locations within the San Pablo Bay, San Francisco Bay, and
Monterey Bay at high tide today. At the San Francisco tidal gauge,
high tide is expected to be 1.5 ft above normal (7.3 ft MLLW) at
11:07 AM Sunday 10/25, including around 1.0 ft of surge residual
partially attributed to impacts from El Nino.
&&
.LONG TERM...
Issued at 1207 AM PDT Sun Oct 25 2026
(Monday through Saturday)
Large-scale troughing persists across the Western US as a low moves
across the Pacific Northwest, and by the middle of the week, a
second developing low over British Columbia will interact with a
decaying low moving in from the central Pacific to reinforce the
troughing. Some light sprinkles are possible in the northern coastal
waters and the adjacent areas of the North Bay on Monday morning as
the low passes by, but most of the impacts will be felt along the
North Coast and across Oregon. Otherwise, highs will start to dip
for the work week, with highs in the inland valleys dropping to the
middle to upper 60s by Monday and the lower to middle 60s for the
second half of the week.
The end of the week into the upcoming weekend is where things get
interesting in terms of the forecast, for it is where the model
outputs start to diverge and the resulting uncertainty ratchets
upward. Comparing mean outputs from two of the global ensemble
models reveals a remarkably different solution across the Western
United States. The European ECMWF ensemble model mean suggests that
the trough will continue handing on through the upcoming weekend
while the American GEFS ensemble model mean depicts a slight ridge
coming in and breaking up the trough's influence by next Sunday, the
first day of November. Ensemble model cluster analysis for Day 7
(Saturday) reinforces this split between a more trough-influenced
solution from the European ensemble members, and a more ridge-
influenced solution from the American ensemble members, with the
members of the Canadian GEPS ensemble model split between the two
with a slight lean towards the American ensemble solution. As a side
note, this whole discussion may illuminate why model output around
and beyond 200 hours is generally considered unreliable by those.
The current forecast shows rain chances coming in Friday into the
upcoming weekend, but with the split between the models that's
pretty much all that can be said with even a moderate degree of
confidence. We will keep a close eye on the forecast, not least
because it could determine whether people need to consider ponchos
or umbrellas as part of their Halloween plans.
Coastal flooding concerns continue across Bayshore locations within
the San Pablo, San Francisco, and Monterey Bays through the next
week, and will expand into the Pacific coastal regions by Monday
through Friday. At the San Francisco tidal gauge, high tide is
expected to be 1.6 ft above normal (7.4 ft MLLW) at 11:39 AM Monday
10/26, 1.8 ft above normal (7.6 ft MLLW) at 12:15 PM Tuesday 10/27,
1.9 ft above normal (7.7 ft MLLW) at 12:56 PM Wednesday 10/28, 1.7
ft above normal (7.5 ft MLLW) at 01:43 PM Thursday 10/29, 1.4 ft
above normal (7.2 ft MLLW) at 2:39 PM on Friday 10/30, and 1.0 feet
above normal (6.8 ft MLLW) at 3:44 PM on Saturday 10/31, including
around 1.0 ft of surge residual partially attributed to impacts from
El Nino.
&&
.AVIATION...
(06Z TAFS)
Issued at 835 PM PDT Sat Oct 24 2026
The evening Oakland upper air sounding showed 0.43" precipitable
water which is near the 10th percentile for late October. Dry air
and a clear sky /VFR/ tonight to daybreak Sunday will allow
radiative cooling which may form a few patches of valley fog /IFR-
LIFR/ early Sunday. Cool air drainage winds i.e. land breezes will
develop tonight and Sunday morning, thermally supported with land
temperatures becoming cooler than sea surface temperatures (lower
to mid 60s, well above October normals). Buoy air temps are
cooler than sea surface temps and cooler air is forecast to
continue over the coastal waters tonight, however it may be
difficult for maritime low clouds to form depending if combined
cooling (mainly from radiative cooling) can reach dew point
temperatures. Cool air drainage breezes may help or may ultimately
move low clouds away from land and mix the low clouds out. 06z
TAFs continue to advertise mainly VFR.
Vicinity of SFO...VFR. West wind 10 to 15 knots decreasing to light
northeasterly late tonight and Sunday morning. West wind 10 knots
late Sunday afternoon and evening.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR. Winds east to southeast 5 to 10 knots
tonight and Sunday morning. West to northwest winds 10 knots Sunday
afternoon and early evening.
&&
.MARINE...
(Tonight through next Friday)
Issued at 828 PM PDT Sat Oct 24 2026
Gentle to moderate northerly breezes persist into early next week
while becoming northwesterly with occasional fresh gusts. Rough
seas will continue to gradually subside to moderate by Sunday and
remain so through much of next week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 3 PM PDT Thursday for CAZ006-506-
508-529-530.
Coastal Flood Advisory from 9 AM Monday to 3 PM PDT Thursday for
CAZ505-509.
PZ...None.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Canepa
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Prepared by Boulder-Creek.com Weather at: Sun Oct 25 02:30:03 PDT 2026
From the National Weather Service
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