FXUS66 KMTR 112316
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
416 PM PDT Fri Sep 11 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1201 PM PDT Fri Sep 11 2026

 - Temperatures near seasonal averages through the next week

 - Breezy onshore winds this weekend

&&

.SHORT TERM...
Issued at 1201 PM PDT Fri Sep 11 2026
(This evening through Saturday night)

The return of the marine layer (around 1600 feet per 12Z OAK 
Upper Air Sounding) resulted in widespread coverage of stratus 
this morning, with the exception of the East Bay interior valleys.
Since then, clouds are quickly retreating to the coast and are 
forecast to linger off of the Central Coast for much of the day. 
However, a weak frontal boundary approaching the North Bay is 
likely to bring a return of clear skies off of the North Bay coast
this afternoon. 

Despite mostly sunny sky conditions across the interior, today 
will be much cooler than previous days as the region remains in 
between mid/upper level cut-off low off of the British Columbia 
coast and high pressure confined to southern California, Nevada, 
and Arizona. Less confidence tonight in the amount of stratus that
returns to the region as the aforementioned frontal boundary 
moves southward and then weakens.

The cut-off low will shift southward before moving into the 
Pacific Northwest Saturday night and into Sunday. As such, 
westerly to northwesterly winds will increase tomorrow afternoon 
and persist through Saturday night ahead of yet another frontal 
boundary. The strongest wind gusts will be between 25 to 35 mph 
with favored gaps, passes, and coastal regions gusts up to 45 mph.
This cold front will sweep across the North Bay and Bay Area 
Saturday night into Sunday with no measurable precipitation 
forecast. 

&&

.LONG TERM...
Issued at 1201 PM PDT Fri Sep 11 2026
(Sunday through next Thursday)

In wake of the frontal passage, offshore flow is forecast from 
Sunday night and into Monday night as 925 mb winds become 
northerly to northeasterly. However, the offshore flow is not 
forecast to be much greater than 20 kt (23 mph) at 925 mb, 
limiting fire weather concerns. Onshore winds are forecast to 
persist in the lower elevations with the strongest in the early 
afternoon and through the evening hours. Thus, the marine layer 
looks to hold around 1500 feet in depth through the weekend. As 
mentioned in the Fire Weather section of the AFD below, areas 
above the marine layer often experience nocturnal drying (during 
the overnight hours). That will be the case during this offshore 
event. The trough axis is forecast to move into the northern 
Rockies and the 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 next week. This will give 
way to temperatures warming 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. 

&&

.AVIATION...
(00Z TAFS)
Issued at 416 PM PDT Fri Sep 11 2026

IFR-MVFR stratus lingers at the immediate coast, with satellite 
imagery revealing clearing skies associated with a weak frontal 
boundary lurking offshore. Will need to monitor the clearing as it 
pertains to stratus development this evening and overnight. As it 
is, the current forecast has a moderate confidence that the stratus 
moves inland this evening as the marine layer remains around 1000-
1500 feet. High resolution models are a little more optimistic in 
terms of keeping inland terminals VFR, but opted to maintain 
continuity with the previous forecast. Any stratus that forms will 
dissipate back to the immediate coast through the course of Saturday 
morning. Moderate onshore pattern winds with some strong gusts will 
continue through the evening hours, turning lighter overnight before 
resuming Saturday afternoon.

Vicinity of SFO... VFR through the day with moderate confidence that 
VFR conditions persist through the TAF period. Moderate northwest 
winds persist into the evening, with wind speeds slightly decreasing 
overnight before strong and gusty winds come to the terminal 
Saturday afternoon.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR with moderate northwest winds through 
the evening, moderate confidence that LIFR ceilings develop 
overnight at the terminals as winds become light. Stratus retreats 
back to the immediate coast on Saturday morning with moderate 
northwest winds resuming in the afternoon. 

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 416 PM PDT Fri Sep 11 2026

Hazardous conditions for small craft will prevail late this
weekend through mid next week. A moderate  to fresh NW breeze will
increase today into tomorrow to a strong  breeze by early Sunday
and continue into the early work week. Near gale force gusts to
occasional 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. Moderate
seas will build, becoming rough, by Monday  in response to the
stronger winds.

&&

.FIRE WEATHER...
Issued at 429 AM PDT Fri Sep 11 2026

A new weather pattern will influence conditions over the Timber 
and Plaskett Fires in Monterey County. The marine layer has 
returned and is 1,600 feet deep as measured by the 12Z balloon. 
This height should be fairly consistent through the day before 
some expansion this weekend as the trough moves through. While the
marine layer brings much cooler and more humid conditions to the 
coast, areas above the marine layer often experience nocturnal 
drying as the dry air above the clouds rolls in simultaneously 
with the low clouds. In the late morning the clouds will mix out 
as the layers become less stratified, often increasing dew point 
during the warmest part of the day.

Flynn

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Saturday for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm-
     SF Bay N of Bay Bridge.

     Small Craft Advisory until 9 PM PDT Saturday for Pt Arena to Pt 
     Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

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

     Small Craft Advisory until 9 AM PDT Saturday 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: Fri Sep 11 16:30:04 PDT 2026