FXUS66 KMTR 261231
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
531 AM PDT Tue May 26 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 1158 PM PDT Mon May 25 2026

 - Cool and cloudy conditions with a chance for coastal and higher
   terrain drizzle through Tuesday morning

 - Strong northerly winds will bring widespread hazardous marine 
   conditions Tuesday

 - Hazardous beach conditions at Pacific Coast beaches Tuesday 
   morning through Wednesday morning

 - Warming and drying trend Friday through Monday

&&

.SHORT TERM...
Issued at 1200 AM PDT Tue May 26 2026 
(Today and tonight)

Tuesday's weather will be brought to you by a cold front. The 
associated lift has already done a number on the marine layer, 
making it too diffuse to support itself. Drizzle/light rain will be 
possible along and ahead of the cold front, especially along the 
coast and in the higher terrain with the help of orographic lift. 
The post-frontal environment will be characterized by clear skies 
and strong northerly winds. Widespread hazardous conditions for 
small craft are expected with gale force winds for the inner waters 
and Monterey Bay. Gusts of 30-40 mph are expected with isolated 
gusts up to 50 mph across the North Bay Interior Mountains and East 
Bay Hills.

&&

.LONG TERM...
Issued at 1200 AM PDT Tue May 26 2026 
(Wednesday through Monday)

The associated upper-level trough will dig into California, becoming 
a cutoff low Wednesday that is expected to remain near-stationary 
through Thursday. As such, Wednesday and Thursday will be very 
similar with below normal temperatures and diurnal winds. Of more 
interest and potential impact is the chance for rain showers and 
thunderstorms. They will both rely on daytime heating as a trigger 
with accumulation dependent on where they develop. Chances are low 
(less than 15%) for thunderstorms with the relatively best chances 
for the far interior. The question is going to be if lift, 
instability, and moisture can overlap spatially and temporally. 
Conditionally unstable lapse rates will yield low CAPE on Wednesday. 
With PWAT values near average (0.60 inches) then, moisture will 
likely be the limiting factor. By Thursday, PWAT values increases to 
near one inch as the low drifts off the coast of the Bay Area; at 
the same time, the atmosphere begins to restabilize likely making 
instability the limiting factor for thunderstorms on Thursday. New 
wildfire starts will be a potential hazard due to fuels being about 
a month ahead of schedule. The low is expected to fill and become an 
open wave by Friday, leaving the region under zonal flow. A much 
warmer and drier airmass arrives over the weekend with upper-level 
longwave ridging moving in from the Eastern Pacific Ocean.

&&

.AVIATION...
(12Z TAFS)
Issued at 530 AM PDT Tue May 26 2026

This is the first morning I'm not writing about widespread stratus, 
but rather a cold front! This system is currently working its way 
down the Bay Area and into the Central Coast. Coastal and higher 
elevation drizzle is possible with the passage of this system in 
addition to brief periods of MVFR to IFR conditions. Behind it, 
conditions are generally VFR with lingering pockets of MVFR cigs, 
but more notably are the gusty northwest winds. These will continue 
to gradually ramp up this morning and then peak during the afternoon 
and early evening hours. Gusts will generally be between 20-30kt for 
most TAF sites, though 30-35kt gusts are possible along the 
immediate coast and at KSFO. Guidance shows the potential for some 
40kt gusts along the coast and at KSFO; however, confidence was not 
high enough to add anything greater than 35kt at this time. Later 
this evening and into the early overnight hours, winds ease and then 
fall at or below 10kt. VFR conditions should prevail, though a few 
models try to bring pockets of stratus back tonight. Low to medium 
confidence in the low forecast this morning and again later 
tonight. Medium to high confidence in the wind forecast.   

Vicinity of SFO...A cold front passed through earlier this morning 
bringing a brief period of drizzle and IFR conditions. In its wake, 
westerly winds have started to pick up while MVFR cigs linger. Cigs 
should gradually lift/mix out over the next couple of hours, leading 
to VFR conditions for the late morning and afternoon hours. Onshore 
winds will hold throughout the day, and increase into the afternoon 
hours. Sustained speeds look to peak around 25kt this afternoon with 
gusts up to 35kt between 20-4Z. Winds will then ease through the 
evening, and then we look at the probability for stratus. Some hi-
res models and MOS guidance suggest we could see a period of MVFR 
cigs tonight. This could arrive as early as 02-6Z or as late as 9Z. 
Opted to hint at the later start but didn't bring in the cigs at BKN 
or OVC. Medium to high confidence in the cloud forecast this 
morning. High confidence in the wind forecast. Low to medium 
confidence in the low cloud timing for tonight. 

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...A cold front will pass through the region 
this morning bringing MVFR and IFR cigs and coastal and mountain 
drizzle. Once the front passes, onshore flow increases and clouds 
lift to VFR criteria. The strongest winds look to occur late morning 
through the early evening. Low clouds look to make a return to the 
region tonight, somewhere between 3-6Z. Opted to go with the later 
start and then keep MVFR cigs through the overnight hours.

&&

.MARINE...
(Today through Sunday)
Issued at 247 AM PDT Tue May 26 2026

A cold front continues to pass over the waters this morning
leading to fresh west to northwest winds with widespread strong
gusts expected over the waters. Winds shift northwesterly and
continue to increase today into Wednesday. This results in strong
to near gale force winds across the outer waters, gale force
winds across the inner waters, and fresh to strong winds across
the San Francisco Bay. Rough seas build to between 12 to 15 feet
Tuesday into late week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from 9 AM PDT this morning through 
     Wednesday morning for CAZ006-505-509-529-530.

PZ...Small Craft Advisory until 3 AM PDT Wednesday for SF Bay N of 
     Bay Bridge.

     Small Craft Advisory until 3 PM PDT this afternoon for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-
     Pt Reyes to Pigeon Pt 0-10 nm.

     Gale Warning from 3 PM this afternoon to 9 PM PDT this evening 
     for Mry Bay-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 until 9 AM PDT this morning for Pt Pinos to 
     Pt Piedras Blancas 0-10 nm.

     Gale Warning from 9 AM this morning to 3 AM PDT Wednesday for Pt 
     Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 9 AM PDT Wednesday for Pigeon Pt to 
     Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...KR
MARINE...KR

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Prepared by Boulder-Creek.com Weather at: Tue May 26 06:30:04 PDT 2026