FXUS66 KMTR 110451
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
951 PM PDT Sun May 10 2026
...New AVIATION...
.KEY MESSAGES...
Updated at 1252 PM PDT Sun May 10 2026
- Warming and drying trend will continue through Monday
- Moderate risk for heat-related illnesses for sensitive
populations across the interior on Monday
- Gradual cooling trend and unsettled weather midweek through
late week
&&
.UPDATE...
Issued at 845 PM PDT Sun May 10 2026
We're keeping an eye on the marine layer tonight as it continues
blossom along the coast. It should deepen to about 1000ft tonight,
which will bring low clouds into portions of the interior valleys.
Guidance shows the clouds mixing out by mid to late morning, which
may impact high temperatures tomorrow.
&&
.SHORT TERM...
Issued at 1252 PM PDT Sun May 10 2026
(This evening through Monday)
Temperatures this afternoon are struggling to reach their forecasted
highs. This is as a deeper marine layer around 1500 ft in the North
Bay and 2000 ft in the Bay Area and Central Coast developed
overnight. Again, where cloud cover lingers or is slow to dissipate
across inland areas is where we are most likely to see cooler
temperatures than previously forecasted. That said, inland clearing
will still allow for temperatures to warm this afternoon as high
pressure to the south of the region continues to strengthen.
Overnight, temperatures will cool into the upper 40s to mid 50s
across most valley locations. Meanwhile, the higher ridges and peaks
will likely bottom out in the upper 50s to 60s. If persistence
holds, low clouds will fill back inland overnight, yet not expecting
as much of an inland penetration as the marine layer is still on
track to compress.
Monday is still on track to be the warmest day of the week, yet we
are seeing less widespread Moderate HeatRisk across the interior.
Mondays afternoon maximum temperatures are expected to be in the mid
80s to lower 90s across the interior with cooler conditions near the
coast as a shallow marine layer and onshore flow will persist.
However, these temperatures could be off by a few to several degrees
where cloud cover develops and lingers. Tricky forecast as high
pressure aloft supports warming afternoon temperatures, yet the
marine influences have been winning out.
&&
.LONG TERM...
Issued at 1252 PM PDT Sun May 10 2026
(Monday night through next Saturday)
The pattern begins to shift Monday night into Tuesday as a trough of
low pressure approaches the Pacific Northwest and northern
California. Thus, temperatures will cool by several degrees on
Tuesday, yet are likely to remain above seasonal averages. A cut-off
low pressure system is forecast to develop and move inland Tuesday
night and into Wednesday bringing even cooler and unsettled weather
to the region. We are still expecting drizzle and/or light rain
Tuesday night through Thursday morning as a result of the mid/upper
level cut-off low moving inland across northern California or the
Bay Area. Rainfall amounts generally will remain less than a few
hundredths of an inch or so.
More of a zonal flow returns by late week and will persist through
the upcoming weekend. This will result in a warming and drying trend
through this timeframe.
&&
.AVIATION...
(06Z TAFS)
Issued at 950 PM PDT Sun May 10 2026
No major changes to the forecast with this TAF package. Tonight's
observations include Mainly VFR conditions with the exception being
along the San Francisco Peninsula and Monterey coastlines where
sites are reporting MVFR to IFR cigs. These will likely hold and
even build for the overnight hours bringing MVFR to IFR ceilings.
The marine layer is expected to be around 1000ft tonight which means
the onset of stratus in the valleys will be delayed or non-existent.
Most sites have hints of cigs, with them lifting by mid to late
morning. VFR conditions are expected for the majority of the region
by Monday afternoon. The marine layer looks to return again tomorrow
evening, opted to hint or fully bring it in for terminals near the
coast. Medium to high confidence in the forecast.
Vicinity of SFO...Westerly winds are winding down and will fall to
around 10kt or less after 6Z. The challenge outside of winds is the
stratus. Satellite imagery and webcams show stratus building around
the San Francisco Peninsula and slowly filtering into the western
portion of KSFO's range ring. With the marine layer expected to be
around 1000ft again, we should see the return of stratus tonight.
Kept the pessimism in the TAFs with IFR cigs based on the last few
nights, but time will tell if go that low or stay in the MVFR
category. Stratus looks to dissipate mid to late morning, with
breezy westerlies of 10-15kt returning Monday afternoon. The marine
layer looks to return Monday night into Tuesday morning, which was
brought into the latest TAF. Medium confidence in the forecast.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...A small band of stratus remains around the
Monterey Peninsula, which has been brought IFR cigs to KMRY. Expect
this to build back in this evening bringing MVFR to IFR cigs to the
terminals. Stratus should begin to erode by mid to late morning,
though a few clouds could linger around KMRY for the afternoon.
Stratus and low cigs look to return Monday evening.
&&
.MARINE...
(Tonight through next Saturday)
Issued at 845 PM PDT Sun May 10 2026
Moderate seas and a fresh to strong northwest breeze with
isolated near gale force gusts continuing through tonight. Winds
ease late tonight across the inner waters then across the outer
waters tomorrow becoming a moderate to fresh northwest breeze.
Seas subside in response, but remain moderate with 4 to 5 foot
seas by mid week.Locally gusty conditions are likely across the
San Pablo and San Francisco Bays where terrain promotes wind
funneling. Winds increase and seas build again late Wednesday into
Thursday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt
Reyes 0-10 nm.
Small Craft Advisory until 3 PM PDT Monday for Pt Arena to Pt
Reyes 10-60 NM.
Small Craft Advisory until 9 AM PDT Monday for Pigeon Pt to Pt
Pinos 10-60 NM.
&&
$$
SHORT TERM...RGass
LONG TERM....RGass
AVIATION...KR
MARINE...KR
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Prepared by Boulder-Creek.com Weather at: Mon May 11 00:30:03 PDT 2026
From the National Weather Service
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