FXUS66 KMTR 221808
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1108 AM PDT Tue Sep 22 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 1201 AM PDT Tue Sep 22 2026

 - Warming trend begins today through Thursday

 - Cooler conditions Friday into the weekend

&&

.UPDATE...
Issued at 904 AM PDT Tue Sep 22 2026

There was coastal drizzle reported at several locations this 
morning, but nothing more than a few hundredths of an inch. Stratus 
pushed well inland into most interior valleys early this morning and 
is forecast to retreat to the immediate coast by late morning/early 
afternoon. This will give way to mostly sunny conditions inland this 
afternoon with temperatures warming into the 60s near the coast, 
upper 60s to low 70s around the bayshore, and mid 70s to mid 80s 
across the interior. Coastal areas will be some 5-10 degrees below 
seasonal averages with the interior holding near average. A warming 
trend remains on tap for Wednesday and Thursday, yet no significant 
heat anticipated with this brief warming trend. 

RGass

&&

.SHORT TERM...
Issued at 1201 AM PDT Tue Sep 22 2026
(Today and tonight)

Extensive stratus has flowed into the North Bay valleys, Monterey 
Bay region, Salinas Valley, Hollister area, and the East Bay west of 
the Berkeley Hills. Across the rest of the SF Bay Area, patches of 
stratus have developed near Livermore and north of San Jose, with 
further expansion expected through the pre-dawn hours. The cloud 
deck retreats back to the immediate coast late this morning into the 
early afternoon, but by the time it develops again tonight, the 
marine layer will be compressed, leading to uncertainty over just 
how far inland the clouds will go. 

The cut-off low that gave us the last couple days of cooler 
temperatures is moving across the state with the center crawling 
through the Mojave Desert into the Great Basin. This allows for more 
zonal flow to come into the state and a warming trend to begin 
today, with high temperatures in the upper 70s to the middle 80s 
across the inland valleys, into the upper 80s in the far interior 
regions of the North Bay and southern Monterey County, the middle 
60s to the middle 70s close to the Bays, and the lower to middle 60s 
along the immediate coast. A breezy onshore wind will develop in the 
afternoon and evening hours, with the strongest gusts of 20 to 30 
miles per hour along the coast, through favored gaps and passes, and 
within the northern Salinas Valley.

As a quick side note, today will mark the autumnal equinox and the 
start of astronomical fall. At 505 PM Pacific time, the sun's 
apparent path on the Earth crosses the equator, giving us 12 hours 
each of sunlight and nighttime.

&&

.LONG TERM...
Issued at 1201 AM PDT Tue Sep 22 2026
(Wednesday through Monday)

Slight ridging will develop over California over the next couple of 
days, and while the ridge axis quickly moves into the Intermountain 
West, the ridge influence will allow for further warming Wednesday 
and Thursday. High temperatures warm into the middle 80s to the 
middle 90s in the inland valleys, the middle 70s to the middle 80s 
close to the Bays, and the middle 60s to the lower 70s along the 
Pacific Coast. Pockets of Moderate HeatRisk are scattered across the 
interior regions, particularly near San Jose, the interior East Bay, 
and the Santa Lucia range. These pockets are not expansive enough to 
merit a Heat Advisory. 

By Friday, a developing trough in the eastern Pacific comes into the 
West Coast, and a cooling trend will cause temperatures to dip near 
and below seasonal averages. Weekend highs range from the middle 70s 
to the middle 80s in the inland valleys and the middle 60s to the 
middle 70s close to the Bays. Temperatures will recover early next 
week as the trough flattens and ensemble model cluster analysis 
hints at a ridge developing somewhere within the western United 
States, although the exact impacts are not certain at this point.

&&

.AVIATION...
(18Z TAFS)
Issued at 1107 AM PDT Tue Sep 22 2026

MVFR to IFR ceilings associated with the marine layer will gradually 
scatter out in the next couple of hours, resulting in widespread VFR 
conditions at most terminals. Low confidence on whether HAF will see 
the sun as there may be a brief period of scattered clouds before 
becoming BKN again. The usual diurnal onshore wind pattern prevails 
through the afternoon with a light south to southwest flow overnight 
across our region. The marine layer will compress overnight. Exactly 
how much is uncertain. Moderate confidence for STS, LVK, SJC, and 
SFO to remain VFR through the TAF cycle with advertised SCT decks 
early Wednesday morning. There is a 60-70% chance for APC and OAK to 
develop BKN ceilings given their exposed locations, though it may be 
intermittent depending on the marine layer depth tonight.

Vicinity of SFO...VFR prevails this afternoon with low to medium 
confidence on the return of MVFR ceilings tonight. Should ceilings 
develop, they will likely roll in around the time of the SCT decks 
as advertised. OAK has a higher probability of developing MVFR 
ceilings early Wednesday morning compared to SFO. Westerly winds 
increase to moderate this afternoon and ease to a light 
southwesterly flow Wednesday morning before increasing again.

SFO Bridge Approach...Current satellite imagery shows a final push 
of stratus across the bridge, but should become VFR in the next hour 
or so. Patchy cloud cover is possible over the eastern side of the 
bridge tonight. Otherwise, similar to SFO.

Monterey Bay Terminals...Borderline MVFR-IFR ceilings linger through 
the next couple of hours with a brief period of VFR conditions. 
Medium to high confidence for an early onset of IFR ceilings around 
4-7 PM PDT impacting MRY first and then SNS. Low confidence on 
whether ceilings will drop to LIFR territory early Wednesday 
morning. For now, the TAF advertises borderline IFR-LIFR with slight 
impacts to visibility due to mist and/or drizzle. Onshore winds 
increase to 7-10 kt this afternoon and gradually become light 
southerly breezes overnight. 

&&

.MARINE...
(Today through Sunday)
Issued at 904 AM PDT Tue Sep 22 2026

Fresh northwest breezes with strong gusts gradually diminish 
across the southern coastal waters by Wednesday morning. Wind 
driven rough seas abate to moderate for a brief period Wednesday 
night into Thursday with widespread moderate northwest winds. By 
Friday, winds increase with building rough seas.

&&

.FIRE WEATHER...
Issued at 434 AM PDT Tue Sep 22 2026

Solid marine layer coverage along the coast and Salinas Valley
overnight. Sounding and profilers put the depth of the marine
layer around the 2,000-2,500 foot range. Definitely some
compression on the marine layer leading to drizzlefest around the
area. Seeing some reduced vsby too, which may lead to patchy fog
early this morning for crews departing ICP for Timber/Plaskett.
Above the marine layer moderate to excellent humidity recovery 
for the most part with the driest conditions above 3,000 feet. 
Otherwise, still valid for a warming and drying trend kicking off 
Tuesday with temperatures up to 10 degrees above normal and areas 
of moderate HeatRisk Wednesday and Thursday. The marine layer will
compress below 1,000 feet during this warm-up with nocturnal 
drying expected above it.

MM

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 5 AM PDT Wednesday for Pt Arena to Pt 
     Reyes 0-10 nm.

     Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this 
     evening for Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory from 3 PM this afternoon to 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.

     Small Craft Advisory from 3 PM this afternoon to 5 AM PDT 
     Wednesday for Pigeon Pt to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Navarrete
MARINE...Navarrete

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Prepared by Boulder-Creek.com Weather at: Tue Sep 22 12:30:03 PDT 2026