FXUS66 KMTR 150456
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
956 PM PDT Fri Aug 14 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 156 PM PDT Fri Aug 14 2026

 - Patchy coastal drizzle late tonight into Saturday morning 

 - Gradual warming trend this weekend into next week, but below
   normal temperatures will prevail

 - Poor overnight humidity recovery across the Santa Lucia and
   Diablo ranges resume early next week
   

&&

.SHORT TERM...
Issued at 156 PM PDT Fri Aug 14 2026 
(This evening through Saturday night)

Improving sky conditions will persist this afternoon as daytime 
heating and mixing gradually erodes the marine stratus from east 
to west. A couple of persistent eddies across Bodega Bay will 
continue to send a feed of stratus into the North Bay. Confidence 
still remains high that clearing will continue here and we'll see 
the MaxT forecast remain on track. Winds continue to climb across 
some of the favored regions of the East Bay and gusts to near 40
mph are probable here. Fuels across this area are dry and there
does remain some fire growth potential here (pending an ignition). 

Broad troughing aloft in tandem with the SFO-SAC/SFO-SMK 
gradients increasing to around 3mb should spell a return of marine
stratus across most of the area, with the exception being some 
elevations above 3000 feet. While overnight humidity recovery into
Saturday will again climb above 60% for many locales, some of the
peaks across the Santa Lucia and Diablo Ranges, as well as the 
Santa Cruz Mountains, East Bay Hills and North Bay Mountains may 
only experience max RH around 40%. This will hopefully help at 
least modulate any ongoing fire activity along the Central Coast 
during the overnight hours, outside of the highest peaks.

The aforementioned troughing in place will instigate orographic 
ascent along the coast and coastal ranges late tonight and into 
the pre-dawn hours on Saturday. Forecast soundings show a moist 
planetary boundary layer along with steep low level lapse rates 
capped by a nearly 20C temperature inversion. This should promote 
pockets of drizzle which may translate to slick road conditions 
and reduced visibility through about 18 UTC on Saturday. Be sure 
to exercise caution if commuting. 

Saturday will start out gloomy and while troughing will persist,
the amplitude of the wave appears a little less than today
(Friday). This should translate to an earlier clearing time and a
potential for greater insolation and thus warmer conditions. 
Temperatures will still be running a good 5 to 15 degrees below 
normal across the area, but it'll be a largely pleasant day. 

&&

.LONG TERM...
Issued at 156 PM PDT Fri Aug 14 2026 
(Sunday through next Thursday)

As we progress into the latter half of the weekend and into next
week, we'll maintain generally southwesterly flow aloft. While the
onshore flow will remain in place, the trough axis will be
displaced father west which may equate to less in the way of
synoptic scale ascent across our area. While I cannot completely
discount the potential for patchy drizzle, I'll forgo mentioning
DZ Sunday and onward at this time. The marine layer may not be
quite as deep at times next week and in fact, the deterministic 
guidance suggest a return to poor overnight humidity recovery (max
RH between 20% and 40%) across the higher terrain of the Santa 
Lucia and Diablo Ranges as well as the East Bay/Santa Clara Hills 
and portions of the North Bay Mountains. Fortunately, there 
doesn't appear to be a strong signal for winds (outside of the
favored gaps and passes), though favorable alignment of fuels 
(which still remain dry) and terrain could support some fire 
growth potential. 

While the trough axis will remain a bit farther to the west,
enough southwesterly flow should keep the Pacific Southwest ridge
in check. While the multi-model ensemble mean keeps the heart of 
the ridge anchored across southern New Mexico and adjacent
portions of west Texas, there are some solutions which place the 
ridge axis closer to the Four Corners. Should this solution 
verify, compression of the marine layer could mean that the 
current MaxT forecast toward the end of the long term period will 
need to be adjusted upward. 

&&

.AVIATION...
(06Z TAFS)
Issued at 955 PM PDT Fri Aug 14 2026

MVFR-IFR stratus is expanding across the region and will impact all 
the terminals through the night into the later part of Saturday 
morning, when inland stratus progressively mixes out leaving coastal 
regions socked in through the daytime. Moderate and gusty onshore 
winds will develop Saturday afternoon and evening. Stratus returns 
to the region Saturday night with lower ceilings expected as a 
thermal ridge begins to compress the marine layer.

Vicinity of SFO... MVFR stratus persists through the night, with 
clearing expected sometime during the late morning or early 
afternoon hours on Saturday. Breezy west-northwest winds will resume 
Saturday afternoon, with stratus returning in the evening to 
overnight hours. Confidence in the stratus clearing and development 
times is low as high-resoluton models suggest that the edge of the 
stratus deck may develop right over the terminal, and lingering 
stratus on the western side of the San Bruno Gap may lead to 
pulses of stratus ceilings during an otherwise VFR period.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... MVFR-IFR ceilings and light winds continue 
through the night and into the late hours of Saturday morning. 
Moderate confidence that MRY remains socked in through the day, with 
the most likely time for scattering between 20-00Z. Moderate 
northwest winds will develop Saturday afternoon and evening. Stratus 
will return to SNS sometime Saturday evening with low confidence in 
the exact timing.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 955 PM PDT Fri Aug 14 2026

Gentle to moderate northwest winds persist through the early part
of next week. Seas will continue to subside and become moderate in
response. A long period southerly swell of about 16 to 18 seconds
approaches the coast tonight into Sunday. Winds increase to a
fresh to strong breeze in the early and middle parts of next week,
causing seas to build up to 9 feet.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Bain
LONG TERM....Bain
AVIATION...DialH
MARINE...DialH

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Prepared by Boulder-Creek.com Weather at: Fri Aug 14 22:30:02 PDT 2026