FXUS66 KMTR 090724
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1224 AM PDT Sat May 9 2026

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

.KEY MESSAGES...
Updated at 1130 PM PDT Fri May 8 2026

 - Warming and drying trend will continue through the early part 
   of next week

 - Temperatures are forecast to peak on Monday

 - Moderate risk for heat-related illnesses for sensitive 
   populations across the interior early next week

&&

.SHORT TERM...
Issued at 1130 PM PDT Fri May 8 2026
(Tonight through Sunday)

The building ridge has called for much less stratus coverage than 
previous nights as the marine layer compresses. Cloud cover will 
still be prevalent along the coast, but will be spottier in the Bays 
and the inland areas. Pockets of fog will still be possible, but 
look to also be spottier than previous nights. Temperatures will 
still be close to average through the night with lows in the upper 
40s to low 50s.

Saturday continues the warming trend due to the weaker marine 
influence, reduced cloud cover, and building ridge. Many more of the 
inland areas to break into the 80s, while coastal areas will stay 
low 60s, and the slightly inland areas stay in the 70s, but most 
areas away from the coast look to break 80. A few of the more inland 
areas look to break into the mid 90s than previous days.

Saturday night will have slightly warmer temperatures and comparable 
marine layer conditions to Friday night/Saturday morning. However, 
the slights more compressed marine layer into Sunday morning will 
cause the overall moisture to be more denser within the marine 
later. This will offer better chances for early morning fog in the 
favored valleys.

The compression of the marine layer and building of the ridge 
continues Sunday leading to temperatures to increase by another few 
degrees in the inland areas, while the coast remains cool in the 60s 
with the help of a good sea breeze and shallow marine layer.

&&

.LONG TERM...
Issued at 1130 PM PDT Fri May 8 2026
(Sunday night through next Friday)

While the marine layer stays intact for Sunday night, the inland 
push of stratus looks to be very modest. Again, valleys will see 
good chances for fog early Monday, but fog looks to mix out by the 
mid morning. The increasing pressure from the ridge will begin to 
form a thermal belt, causing higher peaks to see limited overnight 
cooling with lows in 60s and a few 70s.

Monday is set to be hottest day of the forecast. The ridging patter 
peaks and most of the winds become light for a large portion of the 
region. Most of the interior valleys look to break into the 90s with 
widespread 80s for all but the near-coastal areas seeing the 60s and 
70s. Those higher peaks affected by the thermal belt look to jump 
into the 90s as well with the warm morning lows giving them a head 
start.

The ridge begins to push east, allowing for good cooling Monday night 
as the thermal belt collapses, and a notable cooldown Tuesday. 
However, Tuesday will still be on the hot side, offering 
temperatures similar to Sunday.

From there, models continue to have a bit of a split in the movement 
of an approaching trough. The ECMWF and GFS model and ensemble 
families have the trough and its embedded low pass through the Bay 
Area and most of Northern California. This will offer drizzly 
conditions and much cooler conditions. But models differ on the 
timing, with some calling for this change in the mid week, while 
others slow it way down and hold off until the end of the work week. 
Another possible solution is that the low stays north, preventing 
the drizzle chances, and only offering modest cooling by the mid 
week as the pattern switches to zonal flow.


&&

.AVIATION...
(06Z TAFS)
Issued at 1012 PM PDT Fri May 8 2026

Satellite looks quite different this evening as the stratus clinging 
to the coasts have dissipated, particularly around the North Bay. 
There a few patches linger around Marin County, wit h clear skies 
being observed elsewhere. Weak offshore flow is expected to develop 
over the North Bay tonight, which may hinder any stratus or fog 
development. Some hi-res guidance shows that KSTS may have some 
residual moisture and get a sunrise surprise type of situation, but 
even the depth of the moisture for that has been trimmed back. Opted 
to leave the TAF for KSTS with the sunrise surprise stratus but 
that could be adjusted with subsequent TAF updates. If that is 
the case, VFR conditions are expected over the TAF cycle, if not a
brief period of IFR to MVFR cigs is possible at KSTS. VFR TAFs 
are expected for the interior East Bay terminals. 

HAF will remain MVFR with a period of IFR ceilings taking over until 
late morning Saturday. Moderate onshore winds will persist through 
their TAF period as well.

Vicinity of SFO...Well the stratus ended up being fickle and is now 
reporting as FEW04 SCT011 at KSFO this evening. Confidence is low in 
the forecast for the overnight hours given no models really latched 
on to what happened today. Most guidance and soundings try and 
depict stratus flirting around KSFO, perhaps making a return 
around 9Z. Failing that, the time could be closer to sunrise and 
then only last for a few hours before becoming VFR. Breezy onshore
winds are expected around 20-21Z and should last until 0-3Z with 
gusts up to 25-30kt. Winds ease and the marine layer might try to 
make a return late tomorrow night and into Sunday morning. Medium 
confidence in the forecast. 

SFO Bridge Approach...Similar to SFO. 

Monterey Bay Terminals...IFR ceilings dominate the first half of the 
TAF period with moderate onshore winds. SNS flirts with the boundary 
between MVFR-IFR, but there is high confidence that it will become 
IFR around 11/12Z, so I decided to go more pessimistic in the 
forecast as the models (GFS, LAMP, MOS) are in good agreement with 
one another. Westerly winds will become light overnight before 
picking up again mid-day Saturday. There will be a brief period of 
MVFR conditions late morning Saturday that will eventually scatter 
out for the afternoon. Don't get too comfortable though because our 
marine stratus deck is set to return Saturday evening bringing MVFR 
ceilings to the terminals.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 855 PM PDT Fri May 8 2026

Fresh to strong northwest breezes with occasional near gale force
gusts will continue through the remainder of the weekend along
with building rough seas. Winds become more northerly and fresh to
moderate on Sunday with rough seas beginning to gradually ease
late Sunday into Monday. Gentle to moderate north to northwest
breezes are expected on Tuesday and Wednesday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM to 9 PM PDT Saturday 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...Murdock
LONG TERM....Murdock
AVIATION...Navarrete/KR
MARINE...KR

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Prepared by Boulder-Creek.com Weather at: Sat May 9 02:30:03 PDT 2026