FXUS66 KMTR 131225
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
525 AM PDT Thu Aug 13 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1225 AM PDT Thu Aug 13 2026

 - Near-critical fire weather conditions through Thursday early morning
   across Monterey and San Benito Counties due to high based 
   thunderstorms

 - Up to a 15% chance for elevated rain showers/thunderstorms 
   through Thursday early morning across the Central Coast

 - Cooling trend through Friday will bring well below normal
   temperatures, gradual warming trend through the weekend and
   into next week

&&

.SHORT TERM...
Issued at 1225 AM PDT Thu Aug 13 2026
(Today and tonight)

The upper-level low remains off Point Conception and will continue 
to bring up to a 15% chance for elevated rain showers/thunderstorms 
through early Thursday morning across the Central Coast as it moves 
inland. This will bring near-critical fire weather conditions 
through Thursday early morning across Monterey and San Benito 
Counties. Erratic/gusty outflow winds up to 40 mph can be expected 
with any elevated rain showers/thunderstorms. The main concern is 
lightning which will pose the risk for new fire starts and has the 
potential to hinder operations on the Timber Fire. Smoke from the 
Timber Fire will continue to be transported into the Central Coast 
via light southwesterly winds. Smoke will get trapped under the 
inversion at night/in the morning, making the appearance and smell 
worse. The proximity to the low will allow for a relatively deeper 
marine layer across the Central Coast (2,000 feet) than the Bay Area 
(1,800 feet). Sensible weather wise, the cooling and moistening 
trend will continue through Friday with temperatures well below 
normal. 

&&

.LONG TERM...
Issued at 1225 AM PDT Thu Aug 13 2026
(Friday through Wednesday)

Friday will see the coolest conditions of the week with well below 
normal temperatures and a deep marine layer as upper-level troughing 
persists across the West Coast. By the weekend, upper-level ridging 
will build in to the Desert Southwest and an upper-level low will 
develop well off the West Coast. This will lead to cooler conditions 
with a deeper marine layer in the Bay Area and hotter conditions 
with a more compressed marine layer for the Central Coast. 
Temperatures will remain below normal with the higher terrain 
moderating to near normal with the help of warming 850 mb 
temperatures.

&&

.AVIATION...
(12Z TAFS)
Issued at 524 AM PDT Thu Aug 13 2026

The upper level low continues to pull high level clouds over the 
region, while the marine layer deepens and spreads stratus. 
Terminals generally sit within the MVFR cig territory this morning 
and should hold. A few models show some IFR potential for North Bay 
terminals, but confidence is moderate to low for that. Any stratus 
that has formed is expected to erode or retreat to the coast by mid 
to late morning, with high clouds lingering. Breezy onshore winds 
return this afternoon and into the evening, where we could see 
sustained speeds between 10-15 kt with gusts to 15-25kt. Stratus 
returns tonight, likely onsetting between 01Z-09Z. The later start
times favor interior Bay Area terminals. 


 Vicinity of SFO...The stratus made it to SFO tonight bringing MVFR 
cigs with it. Models differ on how long the stratus holds, with the 
times ranging from 14-16Z. A few low clouds may linger throughout 
the day, with stratus returning tonight due to the deepening marine 
layer. Breezy onshore winds, with gusts up to 25kt possible, return 
mid to late afternoon and continue until sunset. 

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Cigs have been improving tonight, with the 
latest METARs showing MVFR cigs around 1500-2500ft. Look for this to 
continue through the rest of the morning hours, with skies clearing 
by mid to late morning. Onshore flow picks up and should remain a 
bit breezy through sunset. Stratus returns early, and will likely 
fall to MVFR between 01-03Z with IFR cigs being possible after 06Z. 

&&

.MARINE...
(Today through Tuesday)
Issued at 524 AM PDT Thu Aug 13 2026

Fresh to strong northwest winds slacken to moderate to fresh today
with rough seas becoming moderate by the evening. A long period
southerly swell will gradually increase Thursday reaching 16 to 18
seconds (possibly higher at times) by Friday and continuing
through the remainder of the weekend. Visibility may decrease due
to haze and smoke nearby the Big Sur coastline due to the Timber
fire.

&&

.FIRE WEATHER...
Issued at 1225 AM PDT Thu Aug 13 2026

Near-critical fire weather conditions through Thursday early morning 
across Monterey and San Benito Counties due to high based 
thunderstorms. The greatest chance was Wednesday afternoon; however, 
with the upper-level low still off Point Conception, there remains 
up to a 15% chance for another round through early Thursday morning. 
Erratic/gusty outflow winds up to 40 mph can be expected with any 
elevated rain showers/thunderstorms. Lightning will pose the risk 
for new fire starts and has the potential to hinder operations on 
the Timber Fire in Big Sur. The areas of most concern will be in the 
higher terrain above the marine layer (2,000 feet), namely the Santa 
Lucia Mountains and Gabilan Range. Poor minimum daytime relative 
humidity around 30% is expected with nocturnal drying bringing 
little-to-no recovery overnight.

Sarment

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PDT this afternoon for 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: Thu Aug 13 06:30:02 PDT 2026