FXUS66 KMTR 100736
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1236 AM PDT Sun May 10 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 1205 AM PDT Sun May 10 2026

 - Warming and drying trend will continue through early in the 
   week with afternoon temperatures peaking on Monday

 - Moderate risk for heat-related illnesses for sensitive 
   populations across the interior on Monday

 - Gradual cooling trend and potential unsettled weather from 
   midweek through late week

&&

.SHORT TERM...
Issued at 1215 AM PDT Sun May 10 2026 
(Today through Monday)

Let's step back and take a look at the interesting longwave 
pattern over the CONUS - ridge of high pressure covers CA which is
bookended by deep troughs on either side with one near the Great 
Lakes and the other near Gulf of AK. The pattern will hold in the
near term, but will shift with a pattern change on the horizon,
literally. So what does this set up mean for the Bay Area? A ridge
of high pressure in May usually brings dry and mild conditions 
and Sunday is no exception. However, it's the details that matter.
Overnight satellite imagery shows solid stratus along the coast 
working its way inland. The marine layer will likely top out 
900-1200 feet this morning and will be the spoiler for Max T 
potential. Would not be surprised one bit if the marine layer was 
able to squeeze out some drizzle along the coast. Model guidance 
has struggled the last few days regarding Max T and the marine 
layer influence...simply put the forecast was too warm. As such, 
trended temperatures downward from the NBM over inland valleys or
areas that have a pronounced marine layer influence this 
afternoon. Went colder by 3-5 degs, but worried it wasn't under 
cut enough. That being said, do expect the marine layer clouds to
erode back to the coast by this afternoon with inland sunshine 
and coastal clouds. Regardless, if you have outdoor activities to 
celebrate Mother's Day it will be pleasant with inland highs in 
the 70s and 80s and cooler at the coast in the 60s - bring a 
jacket. Could also be a tad breezy this afternoon with the temp 
difference from the coast to interior. Sfc pressure gradients 
remain onshore again, but are forecast to be weaker than Saturday 
where they peaked at 4.2 mb. 

Sunday night through Monday - the center of the upper ridge 
begins to shift toward the Desert SW while the upstream trough 
deepens and inches toward the West Coast. Despite the shift, 
Monday is still on track to be the warmest day of the forecast. 
850 mb temps peak at 20-22C. Mixing those temps to the surface 
under ideal conditions would bring toasty temps. However, we still
have some onshore flow and lingering marine layer. As such, max 
temps will be tempered near the coast and bays, 60s to lower 80s. 
Far interior locations will be in the 90s leading to some Moderate
HeatRisk. 



&&

.LONG TERM...
Issued at 1220 AM PDT Sun May 10 2026 
(Monday night through next Saturday)

The change in the longwave pattern begins to unfold Monday night
into Tuesday. The upper level ridge is being replaced by a robust
and anomalously deep upper low for mid May. Temperatures begin to
drop in response to lower 500 mb heights and cooler 850 mb temps,
but still above normal.

By Wednesday near normal temperatures return thanks to the cut-off low
over the region. Confidence fades on the details of the exact 
placement of the cut-off low...cluster analysis is split with 
some favoring more zonal flow and others farther south with a 
deeper low. Regardless of exact placement, it's clear that temps 
drop and at least some drizzle is likely. A few members even show 
light showers Wednesday afternoon/evening (tstorms to the N).

Zonal flow returns for the second half of the work week leading to
rebounding temperatures and drier conditions. 


&&

.AVIATION...
(06Z TAFS)
Issued at 1005 PM PDT Sat May 9 2026

Tonight, stratus is a bit more expansive, perhaps somewhere between 
500-1000ft already, with IFR conditions along the coast and at KSFO 
already and MVFR cigs near KOAK. Expect the stratus to continue to 
move inland and deepen some, impacting North Bay terminals after 
midnight and into tomorrow morning. MVFR to IFR cigs are expected 
and should clear out mid to late morning. For the interior East Bay 
terminals, the stratus deck will move through overnight resulting in 
MVFR ceilings until Sunday morning. IFR ceilings persist at HAF 
through the night with moderate NW winds. By mid-day Sunday, 
ceilings will lift through the afternoon. The stratus deck is set to 
return again in the evening. The high-level clouds that are expected 
Sunday afternoon should also limit the development of the stratus 
deck for the interior East and North Bay terminals.

Vicinity of SFO...Breezy westerly winds with gusts of 18-22kt will 
be lasting through 8Z. Stratus has locked in around the Bay, with 
cigs ranging from IFR to MVFR. Confidence is high that we will 
remain locked in with stratus tonight; however, there is some 
uncertainty with how long we will be stuck with IFR cigs. Opted to 
lean more pessimistic based on satellite imagery, webcams, and the 
KSFO METAR so far. We could break to MVFR cigs for a period on 
Sunday morning, before VFR conditions return by mid to late morning. 
Breezy westerly winds looks to be on tap again for Sunday, with 
gusts to 22KT from 20-03Z. High clouds move in tomorrow afternoon 
and evening. This may limit stratus development Sunday evening into 
Monday morning. Opted to hint at a later arrival, but this may need 
to be adjusted. 

SFO Bridge Approach...Similar to SFO. 

Monterey Bay Terminals...Widespread IFR ceilings are forecast 
through the night which will scatter out by late morning Sunday. MRY 
will experience another return of MVFR stratus Sunday evening. 
Moderate onshore winds persist through the first half of the TAF 
period with a slight ease overnight before picking up again late 
Sunday morning. High-level clouds will also roll in Sunday 
afternoon, limiting the extent and depth of the marine layer into 
the Salinas valley.&&

.MARINE...
(Tonight through next Friday)
Issued at 906 PM PDT Sat May 9 2026

Moderate seas and fresh to strong northwest breezes with
occasional near gale force gusts will continue through most of
Sunday. Locally gusty conditions are likely across the San Pablo
and San Francisco Bays where terrain promotes wind funneling.
Winds gradually ease starting late Sunday with a gentle to
moderate northwesterly breeze expected early to mid week. Breezy
conditions return to the inner waters late week and seas build mid
to late week.

&&

.MARINE...
(Tonight through next Friday)
Issued at 906 PM PDT Sat May 9 2026

Moderate seas and fresh to strong northwest breezes with
occasional near gale force gusts will continue through most of
Sunday. Locally gusty conditions are likely across the San Pablo
and San Francisco Bays where terrain promotes wind funneling.
Winds gradually ease starting late Sunday with a gentle to
moderate northwesterly breeze expected early to mid week. Breezy
conditions return to the inner waters late week and seas build mid
to late week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM to 9 PM PDT Sunday for Mry Bay.

     Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt 
     Reyes 0-10 nm.

     Small Craft Advisory until 9 PM PDT Sunday for Pigeon Pt to Pt 
     Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Pinos to Pt 
     Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

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

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...KR
MARINE...KR

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Prepared by Boulder-Creek.com Weather at: Sun May 10 02:30:03 PDT 2026