FXUS66 KMTR 251151
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
451 AM PDT Mon May 25 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 135 AM PDT Mon May 25 2026

 - Below normal temperatures with coastal and higher terrain
   drizzle today

 - Upper-level troughing will bring strong northerly winds Tuesday
   and kickoff a gradual warming and drying trend Wednesday

&&

.SHORT TERM...
Issued at 135 AM PDT Mon May 25 2026
(Today and tonight)

The unofficial start of summer sure won't feel like it. Temperatures 
will remain well below normal with the help of a 2,500 feet deep 
marine layer. Stratus will retreat to the coast by late morning with 
a mix of sun and clouds expected for the interior tomorrow 
afternoon. Surface troughing and an approaching cold front will even 
allow for some precipitation - the coast and higher terrain will 
have the greatest chances with the help of orographic lift. It'll 
likely be more in the way of drizzle than light rain; nonetheless, a 
few hundredths is expected at most.

&&

.LONG TERM...
Issued at 135 AM PDT Mon May 25 2026
(Tuesday through Sunday)

Upper-level troughing arrives tomorrow, making it the coolest day of 
the week. Of more impact will be the northerly (drying) winds. Wind 
gusts of 30-40 mph are expected along the coast, across ridgelines, 
and through gaps and passes. Widespread hazardous conditions for 
small craft will result. As the trough digs into the state 
Wednesday, it is expected to become a cutoff low that remains near-
stationary through Thursday. This will support a gradual warming and 
drying trend as northerly winds remain in place. Of more interest 
and potential impact is the thunderstorm threat. Chances are low 
(10% or less) with the relatively best chances for the far interior. 
The three necessary ingredients of lift, instability, and moisture 
will be present. Conditionally unstable lapse rates (~7 degrees 
C/km) will yield low CAPE (~500 J/kg); with most of it presenting as 
surface based CAPE, sufficient daytime heating will be needed. The 
limiting factor will likely be moisture with PWAT values near 
average. 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 area under zonal flow 
with onshore flow over the weekend.

&&

.AVIATION...
(12Z TAFS)
Issued at 451 AM PDT Mon May 25 2026

Stratus blankets most of the Bay Area and Central Coast valleys this 
morning due to the marine layer being around 2500ft. Most sites are 
observing MVFR ceilings, though pockets of IFR ceilings exist. The 
marine layer should take a bit longer to erode today, perhaps with 
sites likely clearing by late morning or early afternoon. A brief 
period of VFR conditions are expected this afternoon and into the 
early evening hours, which is when we'll see increasing onshore 
winds. After that, a weak front approaches the region which should 
bring another round of MVFR ceilings tonight and perhaps drizzle 
along the immediate coast and over the higher elevations. Cigs 
should start to clear as the front exists the region, with VFR 
conditions returning mid to late Tuesday morning. 

Vicinity of SFO...The Bay Area terminals are socked in this morning 
with MVFR ceilings. Ceilings should start to improve by the late 
morning hours, with VFR conditions returning by the early afternoon. 
Some model guidance keeps SFO socked in for the day, but for now 
opted to keep some optimism in the TAF. Increasing onshore winds are 
expected during the afternoon with 12-15kt westerly winds picking up 
between 18-21Z and with gusts up to 25kt expected through 01Z. This 
is when we should see cigs clear to VFR status, with another round 
of MVFR cigs expected for the evening and overnight hours. There is 
quite a bit of uncertainty as to when the cigs will lift Tuesday 
morning, but guidance seems favor between 10-15Z at this time. 
Confidence in the forecast is medium to high through the evening. 
Confidence is medium for the overnight hours and into Tuesday 
morning. 

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR cigs plague the terminals around 
Monterey Bay, as the marine layer holds at about 2500ft this 
morning. Conditions should clear out by mid to late morning, which 
should give us a period of VFR conditions for a few hours this 
afternoon. MVFR cigs return early this evening and then hold into 
Tuesday morning. 


&&

.MARINE...
(Today through Saturday)
Issued at 254 AM PDT Mon May 25 2026

Light west to northwest breezes continue today and become
moderate to fresh northerlies Monday night into Tuesday morning.
Northerly winds continue to increase Tuesday into Wednesday
becoming strong with near gale to gale force gusts expected for
the outer waters. Expect building rough seas on Tuesday and
Wednesday, which look to last through the work week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Tuesday for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 
     NM.

     Small Craft Advisory from 3 AM to 9 PM PDT Tuesday for Pt Arena 
     to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos 
     to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

&&

$$

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

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Prepared by Boulder-Creek.com Weather at: Mon May 25 08:30:03 PDT 2026