669
FXUS66 KMTR 101916
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1216 PM PDT Thu Sep 10 2026

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

.KEY MESSAGES...
Updated at 1215 PM PDT Thu Sep 10 2026

 - Widespread moderate HeatRisk continues through this evening

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

 - Breezy onshore winds forecast for this weekend

&&

.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...
(18Z TAFS)
Issued at 1037 AM PDT Thu Sep 10 2026

Currently VFR with high clouds. Moderate confidence on ceilings on
the cusp of IFR/MVFR returning to bayshore and coastal terminals
tonight. Satellite shows a surprisingly decent push of stratus just
beginning to enter our coastal waters from the north. Reasonable
worst case scenario is a more compressed marine layer will bring
lower ceilings and visibilities (likely LIFR); however, that would
likely remain confined to the immediate coast. Diurnal winds will
prevail.

Vicinity of SFO...Currently VFR with northwesterly flow. Moderate
confidence on a ceiling on the cusp of IFR/MVFR developing tonight.
Diurnal winds will prevail.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently VFR with northwesterly flow at
both terminals. Moderate confidence on IFR ceilings returning
tonight. Diurnal winds will prevail.

&&

.MARINE...
(Today through Tuesday)
Issued at 913 AM PDT Thu Sep 10 2026

Moderate to fresh northwesterly breezes will prevail through
Friday, increasing to become fresh to strong this weekend into
next week. Locally hazardous conditions for small craft today will
expand to become widespread this weekend into next week. Moderate
seas will prevail through the weekend, building to become rough in
the outer waters Monday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 10 PM PDT this evening for CAZ006-502>506-
     508>510-512>518-528>530.

PZ...Small Craft Advisory from 3 AM to 9 PM PDT Friday 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 9 PM PDT Friday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Sarment
MARINE...Sarment

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