FXUS66 KMTR 242309
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
409 PM PDT Thu Sep 24 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 920 AM PDT Thu Sep 24 2026
- Warming trend persists today bringing pockets of moderate
HeatRisk across parts of the Bay Area and Central Coast.
- Cooler conditions arrive Friday into the weekend.
- Near seasonal temperatures early next week.
&&
.SHORT TERM...Issued at 358 PM PDT Thu Sep 24 2026
(This evening through Friday night)
The lack of marine layer development last night (aka our natural air
conditioning) allowed temperatures to reach well into the mid 80s to
90s across the interior mountains and valleys of the
North/East/South Bay and Bay shoreline, with temperatures closer to
the mid 90s across the interior Central Coast. The Pacific coastline
remains under the marine influence, therefore temperatures were
observed in the mid 60s to 70s.
Overnight, the anticipated cold front pushes through our forecast
area. This will bring some relief Friday morning with a thick post-
frontal stratus deck and a prominent onshore push of cool, albeit
dry, air. Despite the frontal passage, dry air aloft will mix out
the majority of low clouds allowing high clouds to dominate the
skies through the afternoon into the evening. Because the main core
of the 500 mb trough remains far north of our area, no significant
impacts are expected with this system. The main impact associated
with the post-frontal environment are strong gusts around 20 to 25
mph along the coast into the SF Peninsula.
&&
.LONG TERM...
Issued at 358 PM PDT Thu Sep 24 2026
(Saturday through next Wednesday)
This weekend, the troughing pattern persists, thereby allowing for
cold air advection to gradually fill into the region. There is
potential for the 500 mb trough to dig more southward over the Bay
Area and Central Coast Sunday into Monday, eventually becoming a cut-
off low southeast of our forecast area. In response, building high
pressure behind the trough may induce a push of weak offshore flow
across the higher terrain in the North and East Bay, initiating
another warming period early next week.
&&
.AVIATION...
(18Z TAFS)
Issued at 1032 AM PDT Thu Sep 24 2026
VFR. The lack of a better defined marine layer has resulted in
VFR conditions regionwide this morning. Onshore winds are forecast
to increase through late morning and become locally gusty at
times this afternoon. Winds ease slightly late in the night before
a dry frontal boundary pushes southward across the region
overnight and into Friday morning. The greatest potential for MVFR
or sub-MVFR conditions will be early Friday morning around HAF,
OAK, and MRY. In wake of the frontal passage on Friday, expecting
an increase north-northwesterly winds.
Vicinity of SFO...VFR through the TAF period. Onshore winds
increase this afternoon and again in wake of the early morning dry
frontal passage. There is a 20-30 percent probability of MVFR
ceilings just before sunrise on Friday, yet the greatest potential
will be over OAK. Thus, have left out of the TAFs at this time.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR. Onshore winds increase this
afternoon and ease after sunset. The greatest probability of sub-
MVFR conditions will be at MRY just before sunrise. Once the dry
frontal boundary passes, any low clouds that do develop will mix
out by around 17Z.
&&
.MARINE...
(Today through Tuesday)
Issued at 1032 AM PDT Thu Sep 24 2026
Light to moderate northerly breezes expected through early
Thursday night. Building high pressure in wake of a passing cold
front will usher in fresh to strong breezes Friday into Saturday
for most of the waters. Near gale force gusts will be possible in
the wind-prone areas nearshore. The stronger winds will lead to an
elevated sea state and hazardous conditions for small craft.
&&
.FIRE WEATHER...
Issued at 450 AM PDT Thu Sep 24 2026
Marine layer is pretty much non-existent overnight. That led much
less RH recovery across the district at both lower and higher
elevations. NGFS gave us a hit earlier in the night as the Timber
Fire had an northern perimeter flare up. Even FireGuard showed the
heat as well. Not completely surprised given temps in the 70s and
RH recovery around 30 pct near Timber. Otherwise, notes for today
will be another mild and dry day across the district. Hottest and
driest across the interior portions. Do expect an uptick with
winds late tonight and Friday as a dry front moves through. Cooler
and wetter for Friday and over the weekend.
MM
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 5 AM PDT early this morning for
Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory until 3 AM PDT Thursday for Pt Arena to Pt
Reyes 10-60 NM.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Friday for Mry Bay.
Small Craft Advisory from 9 AM Friday to 9 AM PDT Saturday for
Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-
Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory from 9 PM this evening to 3 PM PDT Saturday
for Pt Pinos to Pt Piedras Blancas 0-10 nm.
Small Craft Advisory from 9 AM Friday to 3 PM PDT Saturday for
Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60
NM.
&&
$$
SHORT TERM...Navarrete
LONG TERM....Navarrete
AVIATION...RGass
MARINE...RGass
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Prepared by Boulder-Creek.com Weather at: Thu Sep 24 16:30:03 PDT 2026
From the National Weather Service
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