FXUS66 KMTR 230602
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1102 PM PDT Tue Sep 22 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1232 PM PDT Tue Sep 22 2026
- Warming trend continues through Thursday
- Cooler conditions Friday into the weekend
&&
.SHORT TERM...
Issued at 1103 PM PDT Tue Sep 22 2026 (Tonight through Thursday)
Marine layer between 1500-2000 feet deep as of Tuesday evening.
Low clouds cover areas from Point Reyes southward to Big Sur with
a decent push of stratus in SF Bay and the Monterey Bay region
including Salinas valley. There is an increasing northerly
gradient now to about 5 mb from ACV-SFO that is eroding the
stratus from north to south for the North Bay. This is occurring
as high pressure is trying to nose into the region from the
southwest. 850 mb temps warming to around 20-21 celsius with hot
inland temps for the interior Central Coast (90s) with mainly
upper 80s to around 90 for the interior North/South/East Bays on
Weds afternoon. With persistent onshore winds not really a late
September setup where we would expect warm/hot temps at the coast.
Looking at the European extreme forecast index we see no areas of
interest suggesting this is just a typical warm late Sept day on
tap. Models hold onto the warm inland temps for one more day
through Thursday. However by Thursday afternoon a storm well to
our north will induce a strong onshore/westerly push, ushering in
a moderate to strong afternoon/evening seabreeze on Thursday that
will signal relief for the Bay Area while the interior Central
Coast remains warm/hot through Thursday evening.
&&
.LONG TERM...
Issued at 1103 PM PDT Tue Sep 22 2026 (Thursday night through
next Tuesday)
A fairly well defined early autumn dry cold front passage will push
through the region Thursday night into Friday morning. No precip
is forecast for the Bay Area as it remains confined to areas north
of Cape Mendocino. However, enough cooling and mixing aloft to
essentially erode or mix out the marine layer quickly by early Friday
morning. Temps still remain seasonably warm/mild Friday but the
cooling trend will have begun. Weather this weekend looks nice for
the last weekend of September. Certainly no hot weather with
inland temps mainly 70s to lower 80s Saturday/Sunday with enough
cold air aloft and mixing to keep skies sunny with perhaps only
some patchy morning low clouds near the coast and bays.
Early look at next week shows no signal for precip or abnormally
hot weather and no fall offshore wind events. Pattern looks pretty
zonal suggesting temps running near seasonal norms.
&&
.AVIATION...
(06Z TAFS)
Issued at 926 PM PDT Tue Sep 22 2026
The marine layer is difficult to to pin down tonight. It's
expected to compress somewhat under ridging aloft but is also
showing signs of a farther push inland than expected. North Bay
and interior South Bay continue with VFR conditions with low
confidence in IFR ceilings developing late in the overnight toward
sunrise for the North Bay. Moderate confidence in VFR persisting
through the remainder of the forecast period at KSJC and KLVK.
Vicinity of SFO...MVFR/IFR ceilings settled in earlier than expected
and are expected to now persist through mid/late morning
Wednesday with VFR expected into the evening hours after lifting.
Breezy onshore flow develops Wednesday afternoon, then eases by
midnight.
SFO Bridge Approach...Similar SFO.
Monterey Bay Terminals...More typical diurnal pattern is expected with
VFR conditions expected by late morning, with VFR through the
remainder of Wednesday afternoon and early evening, MVFR/IFR
ceilings return after sunset.
&&
.MARINE...
(Tonight through next Monday)
Issued at 926 PM PDT Tue Sep 22 2026
Moderate to fresh northwest breezes will continue to diminish
overnight into Wednesday with persistent rough northwest seas that
will gradually ease to moderate on Thursday. Friday will see an
increase in northwest winds accompanied by seas building back up
to rough, and continuing into the weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 5 AM PDT Wednesday for Pigeon Pt to
Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory until 3 AM PDT Wednesday for Pt Pinos to Pt
Piedras Blancas 0-10 nm.
Small Craft Advisory until 3 AM PDT Thursday for Pt Arena to Pt
Reyes 10-60 NM.
&&
$$
SHORT TERM...RW
LONG TERM....RW
AVIATION...JM
MARINE...JM
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Prepared by Boulder-Creek.com Weather at: Wed Sep 23 04:30:04 PDT 2026
From the National Weather Service
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