Technical NOAA Weather Discussion

FXUS66 KMTR 122315
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
415 PM PDT Sat Sep 12 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1201 PM PDT Sat Sep 12 2026

 - Breezy onshore winds this afternoon through Sunday afternoon

 - Temperatures near seasonal averages through this upcoming week

 - Dry, offshore winds are forecast for the higher terrain Sunday
   night into Monday night

&&

.SHORT TERM...
Issued at 1201 PM PDT Sat Sep 12 2026
(This evening through Sunday night)

As mostly sunny skies have returned to the region, we are 
expected temperatures to warm into the 60s to lower 70s along the 
northwest facing coastal locations and low to upper 70s around the
Santa Cruz region, bayshore, and coastal adjacent valleys. 
Meanwhile, interior valleys are forecast to reach into the upper 
70s to mid 80s with the warmest interior valleys of the Central 
Coast reaching into the low 90s. Onshore wind gusts are forecast 
to reach between 25 to 35 mph in the favored gaps, passes, and 
coastal/higher elevation regions gusts up to 45 mph. This is ahead
of a dry frontal boundary which is expected to move through the 
North Bay late this evening and then across the Central Coast 
Sunday morning. Moderate to high confidence that low clouds will 
not spread inland overnight into Sunday morning (patchy at best), 
similar to this morning. However, the marine layer looks to hover 
between 1,500 and 2,000 feet through the night.
  
By Sunday afternoon, the front is forecast to be south of the 
region with cooler temperatures in the higher elevations while 
slightly cooler for the lower elevations. Onshore winds will 
increase once again tomorrow afternoon and evening with gusts 
potentially exceeding those forecast for today, but only by 5 to 
10 mph. Aloft, a light to gentle offshore breeze (with 
occasionally moderate gusts) is forecast to develop in the higher 
terrain as the mid/upper level trough axis shifts into the 
northern Rockies. These winds are not forecast to be overly 
strong, which will help limit fire weather concerns. 

&&

.LONG TERM...
Issued at 1201 PM PDT Sat Sep 12 2026
(Monday through next Friday)

The trough axis is forecast to move into northern Plains early next 
week, diminishing the offshore wind potential. Lingering troughiness 
along the West Coast will maintain cooler than average temperatures 
for much of the week ahead. As such, temperatures are forecast to 
warm into the 60s to lower 70s along the northwest facing coastal 
locations and low to upper 70s around the Santa Cruz region, 
bayshore, and coastal adjacent valleys. Meanwhile, interior valleys 
are forecast to reach into the upper 70s to mid 80s with the warmest 
interior valleys of the Central Coast reaching into the low 90s. 
Overnight and morning low clouds are expected to reach inland before 
mixing out by the afternoon hours as well through the extended 
forecast period. 

&&

.AVIATION...
(00Z TAFS)
Issued at 415 PM PDT Sat Sep 12 2026

VFR conditions across the region through the evening, and high 
confidence that VFR persists through the TAF period away from the 
immediate coast, where patchy IFR-MVFR ceilings are possible in the 
early morning hours Sunday. Strong and gusty onshore winds will 
persist into the evening hours, with moderate winds overnight into 
the morning before winds tick up again Sunday afternoon. 

Vicinity of SFO... High confidence that VFR conditions persist 
through the TAF period. Strong west to northwest winds gusting to 35 
kt will continue through the evening, with a slight decrease in wind 
speeds early Sunday morning before the strong gusts resume Sunday 
afternoon. 

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR through the evening, low to moderate 
confidence in patchy MVFR stratus in the pre-dawn hours of Sunday 
morning. Moderate and gusty northwest winds will continue through 
the evening hours, turning gentle overnight before strong gusts 
resume on Sunday afternoon at the immediate coast.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 415 PM PDT Sat Sep 12 2026

Hazardous conditions for small craft prevail through the middle of
next week. Fresh to strong winds gradually increase today with
widespread strong winds developing by early Sunday. Widespread
near  gale force gusts are likely Sunday into early Monday with
gale force  gusts are expected along the inner waters from Pigeon
Point to Point  Piedras Blancas, the Monterey Bay, and in portions
of the San  Francisco and San Pablo Bays where terrain promotes
wind funneling.  Winds remain elevated through midweek before
decreasing mid to late  week. Moderate seas will build to between
8 to 10 feet and becoming  rough by Monday in response to the
stronger winds.

&&

.FIRE WEATHER...
Issued at 1201 PM PDT Sat Sep 12 2026

The marine layer was around 1,500 feet in depth per 12Z OAK Upper
Air Sounding. However, stratus coverage did not match the typical
depth this morning and is not likely to again tonight despite the
marine layer forecast to be between 1,500-2,000 feet. A dry 
frontal boundary is forecast to move across the Central Coast 
tonight and into Sunday morning. Ahead of this boundary, we are 
expecting an increase in 925 mb relative humidities which would 
lead to higher humidity over the Timber and Plaskett fires 
overnight and into Sunday morning. Sunday night into Monday night,
a light to gentle offshore breeze (with occasionally moderate 
gusts) is forecast to develop in the higher terrain as the 
mid/upper level trough axis shifts into the northern Rockies. As 
such, areas above the marine layer often experience nocturnal 
drying that will likely continue through early this upcoming week.

RGass

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT Sunday for SF Bay N of Bay 
     Bridge.

     Small Craft Advisory from 3 PM to 9 PM PDT Sunday for SF Bay N 
     of Bay Bridge.

     Small Craft Advisory until 3 PM PDT Sunday for Mry Bay-Pigeon Pt 
     to Pt Pinos 0-10 nm.

     Gale Warning from 3 PM to 9 PM PDT Sunday for Mry Bay-Pigeon Pt 
     to Pt Pinos 0-10 nm.

     Small Craft Advisory until 3 AM PDT Monday for Pigeon Pt to Pt 
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to 
     Pigeon Pt 0-10 nm.

     Small Craft Advisory until 9 PM PDT this evening for Pt Pinos to 
     Pt Piedras Blancas 0-10 nm.

     Gale Warning from 9 PM this evening to 9 PM PDT Sunday for Pt 
     Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory from 3 PM Sunday to 3 AM PDT Monday for Pt 
     Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...DialH
MARINE...Kennedy

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Prepared by Boulder-Creek.com Weather at: Sat Sep 12 16:30:03 PDT 2026
From the National Weather Service