169
FXUS66 KMTR 110441
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
941 PM PDT Thu Sep 10 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 843 PM PDT Thu Sep 10 2026

 - Cooler temperatures, closer to seasonal averages, Friday into
   the weekend

 - Breezy onshore winds this weekend

&&

.UPDATE...
Issued at 843 PM PDT Thu Sep 10 2026

Temperatures are cooling rapidly across the region and some marine
layer stratus has arrived to the immediate coastal areas. While some
interior locations remain relatively warm, further cooling is
expected through the night and especially on Friday night, and high
temperatures on Friday are not expected to be as high as today`s. As
a result, we have cancelled the Heat Advisory.

DialH

&&

.SHORT TERM...
Issued at 1215 PM PDT Thu Sep 10 2026
(This evening through Friday night)

After a warm start to the day, the interior will remain very warm
to hot with the ongoing Heat Advisory still in place until 10 PM
PDT this evening. However, we are already seeing cooler conditions
near the coast as a shallow marine layer is forecast to return as
well as an increase in onshore winds.

Tonight, temperatures are forecast to cool into the mid 50s to
near 60 deg F near the coast and across the interior valleys.
However, the higher elevations look to only cool into the 70s and
potentially the lower 80s. Coastal stratus and/or fog look to
develop along the coast and potentially into the North Bay Valleys
overnight as the marine layer deepens to around 500 feet.

On Friday, depending on how much stratus/fog develops in the
morning, the cooling trend will continue with temperates
moderating to near seasonal averages with mostly sunny conditions
across the interior. This is a result of the mid/upper level
through deepening off of the Pacific Northwest coast and high
pressure over the Desert Southwest being suppressed to the south.

&&

.LONG TERM...
Issued at 1215 PM PDT Thu Sep 10 2026
(Saturday through next Wednesday)

The gradual cooling trend will continue into the weekend as the
low pressure off of the Pacific Northwest coast deepens further,
bringing rainfall to that region. This will allow the marine layer
to deepen as well, reaching around 1500 feet by Saturday night
into Sunday. This would also bring increased afternoon and evening
winds in the favored valleys, peaks, passes, and gaps.

Beyond this weekend, troughing off of the West Coast looks likely
to persist. This will allow for afternoon maximum temperatures to
be near to slightly below average and overnight minimum
temperatures to be near or slightly above.

&&

.AVIATION...
(06Z TAFS)
Issued at 935 PM PDT Thu Sep 10 2026

Shallow marine layer is hugging the coast and beginning to slowly
ooze inland. Initial impacts are mainly to HAF with IFR
conditions. IFR will prevail well into Friday for HAF with some
sct late Friday evening. Elsewhere, VFR will persist for the first
few hours tonight before stratus move farther inland dropping cigs
to MVFR/IFR, except far inland LVK/SJC/APC. VFR expected tomorrow
afternoon. Some uncertainty in the extended as the marine layer
struggle with a strengthening n to s tightening gradient. Overall
conf is moderate. Marine layer depth will likely be in the
700-1000 foot range.

Vicinity of SFO...VFR. Will bring cigs in late with some impacts
to the Friday AM rush. Clearing will be early Friday afternoon.

SFO Bridge Approach...Similar to SFO. Far S end of approach may be
more SCT than BKN/OVC Friday AM.

Monterey Bay Terminals...Eddy is forming in the bay, which may
delay initial push of stratus but expecting cigs by Friday
morning. Clearing to VFR will be mid afternoon.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 843 PM PDT Thu Sep 10 2026

Northerly flow will increase over the coastal waters through
Friday leading to moderate to fresh breezes. Winds will increase
further this weekend and become fresh to strong. The stronger
winds will produce locally hazardous conditions for small craft
Moderate seas will prevail through the weekend, building to
become rough in the outer waters Monday. A longer period southerly
swell will mix into the sea state due to tropical systems in the
Pacific.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 AM Friday to 3 AM PDT Saturday for
     Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory from 9 AM to 9 PM PDT Friday for Pigeon Pt
     to Pt Pinos 0-10 nm.

     Small Craft Advisory until 3 AM PDT Saturday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...MM
MARINE...MM

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