797
FXUS66 KMTR 261152 AAA
AFDMTR

Area Forecast Discussion...UPDATED
National Weather Service San Francisco CA
452 AM PDT Sat Sep 26 2026

...New AVIATION, MARINE, FIRE WEATHER...

.KEY MESSAGES...
Updated at 1238 PM PDT Fri Sep 25 2026

 - Cooler conditions through the weekend

 - Warmer temperatures next week

&&

.SHORT TERM...
Issued at 1154 PM PDT Fri Sep 25 2026
(Tonight through Sunday)

Cooler air continues to move in on northwest winds; the ACV-SFO
pressure gradient is 3.4 mb and SFO-SAC is 1.9 mb. Cooler air is
combining with nocturnal radiative cooling and upsloping winds
forming patchy low clouds and mist. Radiative cooling will also
help result in patchy valley fog forming overnight and Saturday
morning.

On average our Sep weather pattern has been influenced by large
scale troughing, with many areas away from the coastline benefiting
from below Sep normals for the month to date. If you`re enjoying
the weather, it`s a nice weekend shaping up with Saturday daytime
highs in the 60s/70 at the coast, mostly 70s inland except in the
80s across the southern interior of Monterey and San Benito
counties. Also for Sunday daytime highs will be below late Sep
normals with highs mainly in the 60s and 70s, quite nice, it could
be warmer/hotter this time of year.

&&

.LONG TERM...
Issued at 1154 PM PDT Fri Sep 25 2026
(Sunday night through next Friday)

Cool temperatures carryover into Monday, then warming returns
Tuesday through late week with increasing 500 mb ridging. Dry
weather is forecast during this timeframe. Daytime highs Tuesday
through late week will warm back to the 80s to lower 90s inland
while it`ll be cooler nearer the coast with highs generally in
the upper 60s and 70s.

&&

.AVIATION...
(12Z TAFS)
Issued at 420 AM PDT Sat Sep 26 2026

Pockets of MVFR have developed this morning across the Napa River
Valley and bayshore portions of the East Bay (including APC and
OAK) thanks to clear skies and sufficient low level moisture. The
depth of this moisture is shallow per our presently ascending
weather balloon from OAK and should translate to clearing roughly
between the 15-17Z timeframe. MVFR cigs are more probable to
linger at KHAF through at least 21Z, though there`s some
indication that VFR may not return today. A storm system will
approach the region toward 12Z Sunday, resulting in VFR ceilings
around FL120. Moisture above the marine layer (roughly around
1,000-1,500 ft) to around 12,000 ft is minimal. However,
noteworthy lift will translate to moistening of this layer with a
potential for weak convection capable of pockets of turbulence and
virga below FL120.

Vicinity of SFO...MVFR cigs are anticipated (and will at times be
intermittent) through 17Z with moderate confidence that VFR will
return by 18Z today. Winds today are anticipated to be a bit more
subdued through the San Bruno Gap. A compact upper low will
approach early Sunday morning during the 24-30 hour portion of the
SFO TAF. Onshore flow is expected to encourage more of a marine
MVFR cigs push, with another cig, albeit VFR, around FL120.
Virga/turbulence below cloud base cannot be ruled out.

SFO Bridge Approach...Clouds are probable to impact the approach
from PAO and SQL, though it appears that areas near SJC will
remain SKC. Clearing is expected by the 17Z-18Z time frame.

Monterey Bay Terminals...Remnant turbulence in the wake of Friday`s
cold front has disrupted fog development and the current TAF set is
slightly more optimistic, especially at KSNS. Occasional IFR
stratus is still anticipated to persist through at least the 15Z
at MRY. The approach of an upper storm system should encourage
stronger onshore flow and result in MVFR ceilings. While guidance
does suggest a 02Z-03Z window, the marine layer is likely to
struggle to re-develop after a couple of days of dry continental
flow and it`s probable that this initial surge will be
intermittent. The current TAF set estimates that the best window
for more persistent cigs to be closer to 04Z. MVFR will prevail
through sunrise Sunday. While the potential for IFR is too low to
include at this juncture, it`s non-zero and we`ll monitor trends
in guidance for potential inclusion in subsequent TAF issuances.

&&

.MARINE...
(Today through Thursday)
Issued at 420 AM PDT Sat Sep 26 2026

Fresh to strong northerly breezes are forecast to continue
through the weekend. This will equate to hazardous boating
conditions, especially for waters beyond 10 nautical miles from
the shoreline. Near gale forced wind gusts will be ushered in
behind a departing upper storm system early next week. The
strongest gusts are expected across northern outer waters.

&&

.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...Canepa
LONG TERM....Canepa
AVIATION...Bain
MARINE...Bain
FIRE WEATHER...Bain

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