FXUS66 KMTR 010014
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
514 PM PDT Mon Aug 31 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1250 PM PDT Mon Aug 31 2026

 - Well below normal temperatures through Friday, gradual warming
   and drying trend this weekend

 - Beneficial wetting rain in the North Bay Tuesday through
   Thursday, drizzle/light rain possible elsewhere

&&

.SHORT TERM...
Issued at 1250 PM PDT Mon Aug 31 2026
(Monday through Friday)

Upper-level shortwave troughing will swing into Northern California 
tomorrow; this will result in temperatures well below normal, a 
chance for drizzle/light rain, and widespread cloud cover. The best 
chances for drizzle/light rain will be in the North Bay, 
particularly along the coast and in the higher terrain with the help 
of orographic lift. A reinforcing upper-level low and an attendant 
cold front will approach the area Wednesday into Thursday. This will 
keep well below normal temperatures and cloudy conditions around and 
likely make the marine layer arbitrary. There will be a better 
chance for drizzle/light rain with this round with a lifting 
mechanism in place as PWAT climbs to near one inch (90th 
percentile). It is likely (60+% chance) that the northwestern half 
of the North Bay gets wetting rain (0.10 inches) between now and 
then. While rainfall is expected to be beneficial, wet roadways will 
create slick driving conditions and increase stopping distance.

&&

.LONG TERM...
Issued at 1250 PM PDT Mon Aug 31 2026
(Saturday through Sunday)

Global ensemble clusters diverge on solutions dramatically going 
into the weekend, specifically on low vs trough and the location and 
timing of the feature, so basically everything. What is certain is 
that the region will be under the influence of some kind of 
troughing through the weekend. As it weakens through the weekend, a 
gradual warming and drying trend will commence with temperatures 
moderating to slightly below to near normal. Beyond the seven day 
forecast and into Labor Day/early next week, Invest EP95 well 
offshore of Southwestern Mexico becomes a variable. Uncertainty over 
the weekend will compound and propagate into the tropical side of 
the forecast, making it impossible to talk specific impacts at this 
point in time. The primary impacts would likely be rain and wind 
with impacts likely decreasing from south to north.

&&

.AVIATION...
(00Z TAFS)
Issued at 514 PM PDT Mon Aug 31 2026

VFR everywhere expect for HAF, SFO, and OAK where MVFR ceilings 
prevail. Marine stratus is expected to make another push this 
evening with MVFR ceilings developing at most terminals during the 
post-sunset hours and overnight. Low to medium confidence on the 
onset times for MVFR ceilings given the current stratus feed over 
the ocean is rather disorganized. Diurnal onshore winds persist 
through the TAF period with APC and LVK continuing to experience 
gusts around 20 kt this evening. Stratus is expected to scatter out 
late tomorrow morning into the early afternoon.

Vicinity of SFO...MVFR ceilings prevail through Tuesday morning with 
moderate onshore breezes. Stratus coverage may intermittently become 
VFR this afternoon, but should become solid MVFR around sunset time. 
Leaned on an optimistic clearing time for Tuesday morning, though 
confidence is low.

SFO Bridge Approach...Patchy stratus coverage is expected to 
continue into the evening. Otherwise, similar to SFO.

Monterey Bay Terminals...VFR is anticipated through the early 
evening hours before marine stratus re-develops. Forecast confidence 
is low to medium as the current satellite presentation of stratus is 
very disorganized. At this time, the expectation is that stratus 
will invade KMRY just after sunset this evening, with MVFR arriving 
a few hours after that at KSNS. While IFR is a possibility, the 
current TAF set leans on a more optimistic ceiling forecast given 
the amount of dry air likely just above the marine layer. Otherwise, 
diurnal breezes with speeds of 8-12 knots are advertised throughout 
the TAF cycle. 

&&

.MARINE...
(Tonight through next Sunday)
Issued at 514 PM PDT Mon Aug 31 2026

Northwest to westerly gentle breezes will persist through the
week with intermittent periods of moderate breezes. Wind driven
seas are anticipated to remain slight to moderate through the
week with long period southerly swell persisting thanks to
tropical cyclone activity.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Tuesday for SF Bay N of Bay 
     Bridge.

     Small Craft Advisory until 9 PM PDT this evening for Mry Bay.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...Navarrete/Bain
MARINE...Bain

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Prepared by Boulder-Creek.com Weather at: Mon Aug 31 20:30:02 PDT 2026