FXUS66 KMTR 221152
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
452 AM PDT Fri May 22 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1200 AM PDT Fri May 22 2026

 - Diurnally driven onshore winds during the afternoon and early
   evening

 - Warm and dry weather today leads to elevated fire weather
   concerns for the interior Bay Area and Central Coast

 - Gradual cooling trend begins today with seasonal temperatures
   for the upcoming weekend and cooler temperatures early next
   week

&&

.SHORT TERM...
Issued at 1200 AM PDT Fri May 22 2026
(Today and tonight)

The stratus deck has completely covered the coast and is flowing 
through the Petaluma Gap into the Sonoma County valleys, through the 
Golden Gate into the Berkeley area, and across the Monterey Bay 
region and up the Salinas Valley. The Bodega Bay profiler reports a 
marine layer around 1000-1500 ft thick, which would allow stratus to 
fill into the North Bay Valleys, the East Bay west of the Berkeley-
San Leandro Hills, the Santa Clara Valley, and perhaps impacting the 
area around Hollister over the course of the night before stratus 
retreats to the immediate coast through the post-sunrise hours this 
morning.

An upper level ridge over the northern Pacific that extends into the 
Pacific Northwest is continuing to flatten under the influence of a 
trough centered over Alaska, allowing a gradual cooling trend to 
begin today. NBM model output continues to run a little warm, so I 
have tamped down today's high temperature forecasts. They're still a 
shining example of the impact of the Bay Area and Central Coast's 
famous microclimates, with high temperatures ranging from the middle 
80s to the lower 90s in the inland valleys of the Bay Area and 
Central Coast, to the upper 50s to lower 60s along the Pacific 
Coast. In between the two are the North Bay valleys, where highs 
range from the middle 70s to lower 80s, the Bayshore regions where 
highs range in the 70s, tending warmer the closer you get to the 
southern edge of San Francisco Bay, and downtown San Francisco 
itself where temperatures top out around the middle 60s. Breezy 
onshore winds will develop during the afternoon and evening hours, 
with gusts up to 15 to 25 mph through favored gaps and passes.

Continuing hot and dry conditions across the interior regions will 
contribute to another day of elevated fire weather concerns. For 
those living or visiting those hot and dry regions, keep the 
following in mind:

* Properly dispose of cigarettes and matches
* Do not use a lawn mower on weeds or dry grass
* Avoid using equipment that creates sparks
* Make sure campfires are completely put out
* Make sure no vehicle parts drag on the ground, including towing 
  chains
* Obey burn bans & only burn with a permit

&&

.LONG TERM...
Issued at 1200 AM PDT Fri May 22 2026
(Saturday through Thursday)

The aforementioned cooling trend continues through the early part of 
next week, and by Saturday, temperatures should be near the seasonal 
average with highs in the middle 70s to the middle 80s inland. Early 
next week, a cold front associated with a deep upper low is expected 
to make its way through the region, and the ensemble model runs are 
starting to agree on a period of cooler temperatures and stronger 
onshore flow Monday through Wednesday. The slight chance for light 
rain or drizzle continues across favored coastal regions as the 
front passes through, as is the concurrence of the models that any 
rainfall that develops will be very light with few hundredths of an 
inch being a reasonable higher end amount for any region.

Towards the later part of the week, the ensemble model runs begin to 
diverge as the evolution of the upper level low and incoming ridging 
becomes uncertain. Most runs lean towards a warming trend for that 
period, which is reflected in the current forecast, with a 
significant minority (around 30-40% of the runs) suggesting that 
some form of trough lingers through the period.

&&

.AVIATION...
(12Z TAFS)
Issued at 450 AM PDT Fri May 22 2026

Solid marine layer push overnight, one of the bigger pushes as of
late. That being said, LVK and SJC have the best chc of remaining
VFR this AM. The marine layer may have solid intrusion, but still 
remains on the shallow side. Expect mid to late morning clearing 
most areas except the immediate coast. VFR this afternoon with 
early return this evening and overnight. Low conf remains on CIGs 
for LVK and SJC again tonight.

Vicinity of SFO...Tricky and low conf forecast this morning as
the terminal is in a stratus deck hole with clouds on the
periphery creeping inward. Hi-res and prob guidance shows a slight
chc (20-30%) of CIGs arriving in the 12-13Z time and clearing 
16-17Z if they do arrive. If CIGs do come they'll be low and under
1k ft. Given the lower conf and transient nature went with a 4 hr
tempo. VFR this afternoon. Conf is low again for tonight as 
guidance shows a similar scenario again. 

SFO Bridge Approach...Way more clouds over the approach into the 
AM rush. It'll be close, but aircraft may hold onto visuals until
the bridge and possibly make it to the runway. Cloud bases are
under 1k and marine layer detection shows cloud tops in the
1200-1500ft.

Monterey Bay Terminals...LIFR cig mid morning then VFR. Early
return of CIGs this evening. 

&&

.MARINE...
(Today through Wednesday)
Issued at 426 AM PDT Fri May 22 2026

Northerly breezes winds will continue to ease north of Point
Reyes today. Elsewhere winds will shift to southwesterly and
remain light to gentle. The sea state will improve heading into
the holiday weekend as northwesterly swell continues to decrease.

&&

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

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...MM
MARINE...MM

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Prepared by Boulder-Creek.com Weather at: Fri May 22 06:30:03 PDT 2026