FXUS66 KMTR 231138
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
438 AM PDT Sun Aug 23 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1204 AM PDT Sun Aug 23 2026
- Temperatures near to slightly below seasonal averages persist
within the marine layer through the next week
- Warm and dry conditions continue above 1000 feet
&&
.SHORT TERM...
Issued at 1204 AM PDT Sun Aug 23 2026
(Today and tonight)
Another day of the weather pattern dominated by the balance between
the ridge over the Desert Southwest and the troughing over the
Eastern Pacific. Today, a cutoff low moving across the Pacific
Northwest is allowing the ridging to have a little more impact over
central California, resulting in a compressed marine layer and a
slight uptick in temperatures across the interior. Some coastal
stratus development is still possible through the overnight hours,
and any stratus that does form will dissipate rather early in the
post-sunrise hours. High temperatures today range in the middle 80s
to the middle 90s across the interior, the upper 90s into the triple
digits in the warmest interior spots (especially southern Monterey
County), the 70s and lower 80s near the Bays, and the lower to
middle 60s along the Pacific coast. Breezy onshore winds are
expected in the afternoon and evening along the coast and through
favored gaps and passes.
Regarding conditions near the Timber Fire, the compressed marine
layer will lead to warm and dry conditions in the higher elevations
where the fire continues to actively burn. Light northeast winds in
the morning will shift to a southwest flow in the afternoon and
evening hours. Smoke transport will be inhibited by the marine layer
inversion into the morning, resulting in the potential for reduced
visibilities in the immediate area, while winds aloft will transport
smoke northeastward towards Salinas and Hollister. For air quality
information, refer to products issued by the Monterey Bay Air
Resources District.
&&
.LONG TERM...
Issued at 1204 AM PDT Sun Aug 23 2026
(Monday through Saturday)
The pattern remains relatively stable through the rest of the
forecast period. A developing low in the eastern Pacific will allow
more of the troughing influence to arrive on Monday, causing
temperatures to dip by around 3-6 degrees in the inland valleys
(around the lower 80s to the lower 90s), before temperatures rebound
on Tuesday and Wednesday due to the ridging reasserting itself, and
remain remarkably close to today's forecast through the end of the 7-
day outlook. The breezy afternoon and evening winds will continue to
develop for coastal areas and through favored gaps and passes.
Ensemble models and our colleagues at the National Hurricane Center
continue to suggest the possibility for a couple of tropical systems
to develop off the coast of Mexico through the next week. One such
system could very well develop today. It's too early to say what the
impacts of the system could be to the region, ranging from impacts
to the large-scale pattern to the potential for tropical moisture
flow towards our region.
&&
.AVIATION...
(12Z TAFS)
Issued at 433 AM PDT Sun Aug 23 2026
Currently a mixed bag of LIFR-VFR. Warmer and drier conditions are
inhibiting stratus formation this morning and high clouds streaming
in from the southwest are not helping. As a result, confidence is
decreasing in the widespread return of IFR/MVFR stratus this
morning. OAK, SFO, and STS have been reduced to TEMPO groups for IFR
stratus through 16Z with APC, LVK, and SJC likely remaining VFR.
Coastal terminals of HAF, MRY, and SNS can expect ceilings on the
cusp of LIFR/IFR. Due to the patchy nature of stratus, VFR will
likely be achieved earlier than normal. Diurnal winds will prevail.
A more normal stratus intrusion is expected tonight, leading to
moderate confidence in ceilings (likely on the cusp of
IFR/MVFR) returning to most terminals.
Vicinity of SFO...Currently VFR with westerly flow. Confidence
continues to decrease on a ceiling developing at the terminal this
morning with the camera showing stratus holding to the northwest. If
it is able to develop, it'll likely be on the cusp of IFR/MVFR.
Diurnal winds will prevail. Higher confidence on a ceiling on the
cusp of IFR/MVFR returning tonight.
SFO Bridge Approach...The San Mateo Bridge Approach will likely stay
VFR longer than the terminal this morning with patchy stratus along
the East Bay Hills.
Monterey Bay Terminals...Currently LIFR with southwesterly flow at
MRY and VFR and calm at SNS. SNS is expected to get a ceiling on the
cusp of IFR/LIFR. VFR is expected by late-morning with an early
return of IFR stratus this evening. Diurnal winds will prevail.
&&
.MARINE...
(Today through Friday)
Issued at 433 AM PDT Sun Aug 23 2026
Fresh to strong northwesterly breezes will keep hazardous
conditions for small craft in the outer waters through this
morning. Northwesterly breezes will diminish this afternoon with
hazardous conditions for small craft remaining confined to the
northern outer waters through Monday morning. Slight to moderate
seas will prevail. Reduced visibility is expected along the Big
Sur Coast from the Timber Fire.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt
Reyes 10-60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Sarment
MARINE...Sarment
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Prepared by Boulder-Creek.com Weather at: Sun Aug 23 06:30:02 PDT 2026
From the National Weather Service
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