FXUS66 KMTR 071111
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
411 AM PDT Wed Oct 7 2026
...New AVIATION, MARINE, FIRE WEATHER...
.KEY MESSAGES...
Updated at 0103 AM PDT Wed Oct 7 2026
- Hazardous heat inland persists through Thursday, never leave
children or pets in unattended vehicles!
- Elevated fire weather conditions persist in the interior
through Thursday
- Coastal flooding concerns due to astronomical tides and thermal
expansion through the weekend
- Hazardous beach conditions along Pacific coastline later this
week into the weekend due to long period swell
&&
.SHORT TERM...
Issued at 103 AM PDT Wed Oct 7 2026
(Today and tonight)
The marine layer remains shallow and compressed tonight with only
inland intrusion on satellite over the Monterey Bay into the
Salinas Valley. KHAF is reporting 1/4mi vis in fog, KOAR is
reporting 1/2mi and KMRY is down to a mile vis, thus can't rule
out another Dense Fog Advisory along the Pacific Coast at some
point over the remainder of the overnight into Wednesday morning.
The Heat Advisory remains in effect with high pressure still
draped over our area, however later tonight, a weak upper level
disturbance begins to encroach on the ridging pattern as it moves
east today. Marginally improved onshore flow will bring more
stratus into the North Bay and Bay Area later tonight than we've
seen the past few nights, with the potential for more widespread
impacts from fog possible into Thursday morning.
&&
.LONG TERM...
Issued at 103 AM PDT Wed Oct 7 2026
(Thursday through Tuesday)
Although the aforementioned weak upper level disturbance will help
break down the ridge it won't ultimately make it to the coast,
instead it will be pulled south into a merger with the remnants of
Rachel by the weekend. The hot temperatures will linger Thursday
with no changes anticipated for the Heat Advisory to come to an end
Thursday night.
The cooler temperatures through the weekend will be welcomed as
temps return to more seasonal averages. An interesting synoptic
pattern begins to unfold by Sunday into the beginning of next
week. A series of mergers is set in motion, beginning with Rachel
moving onshore. The Polar Jet trough absorbs the remnants of
Rachel while moving entirely over our area (was farther east in
prior deterministic output) with increasing confidence in
scattered light rain, especially for the Central Coast Sunday
night into Monday. While the upper level low producing our
rainfall begins its shift east it will then merge with
'Disturbance 1' as it moves into the Desert Southwest. The upper
level low impacting us this weekend will bring gusty winds into
our typical valleys, gaps and passes with very strong winds
possible above 50 MPH for elevated portions of the East Bay both
Friday night and Saturday night.
&&
.AVIATION...
(12Z TAFS)
Issued at 410 AM PDT Wed Oct 7 2026
Currently LIFR-VFR. Dense fog has been observed at the coastal
terminals of HAF, MRY, and SNS overnight; however, an eddy has
pulled it away from the Monterey Bay terminals. As such, TEMPOs
remain in place for dense fog at MRY and SNS through 16Z with it
prevailing at HAF through 17Z. Persistence forecast on tap tonight
with a compressed marine layer keeping bayshore and interior
terminals VFR while LIFR returns early to the coastal terminals.
Diurnal winds will prevail.
Vicinity of SFO...Currently VFR with westerly flow. High confidence
in VFR and diurnal winds prevailing through the TAF period.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Currently VFR and calm at both terminals.
An eddy has peeled dense fog back to the immediate coast, leading to
VFR at the terminals. With the close proximity, have opted to go
TEMPO in case it's able to remain on the edge and/or push back in.
High confidence in VFR by 18Z; however, reasonable best case
scenario is it'll be closer to 16Z or even earlier based on
persistence, current trends, and the shallow nature of the marine
layer. Persistence forecast on tap tonight with an early return of
LIFR ceilings by 03Z. Diurnal winds will prevail.
&&
.MARINE...
(Today through Monday)
Issued at 410 AM PDT Wed Oct 7 2026
Gentle to moderate northerly breezes and moderate seas will
prevail through Thursday. Strong to near gale force northerly
winds will develop across the northern outer waters Friday,
spreading across the rest of the waters Saturday into Sunday.
Rough to very rough seas will build Friday into the weekend as a
result. Long period southerly swell arrives Friday with long
period westerly swell arriving Sunday.
&&
.FIRE WEATHER...
Issued at 410 AM PDT Wed Oct 7 2026
Hot and dry conditions will lead to elevated fire weather conditions
across the higher terrain through Thursday. Temperatures 10 to 20
degrees above normal and poor minimum relative humidity will
continue away from the compressed marine layer at the coast. The
higher terrain will experience active thermal belting, little-to-no
recovery with nocturnal drying across the highest peaks, and thus
prolonged burn periods. Winds remain the limiting factor, with
diurnal winds prevailing except for light northerly/offshore flow
overnight across the higher terrain. ERC values will rise to near
records during the hot and dry conditions. A pattern change Friday
into the weekend will bring cooler, moister, and windier
conditions.
Sarment
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Dense Fog Advisory until 9 AM PDT this morning for CAZ006-505-
509-528>530.
Heat Advisory until 10 PM PDT Thursday for CAZ503-504-506-508-
510-512>518.
Coastal Flood Advisory until 1 PM PDT Thursday for CAZ506.
PZ...Dense Fog Advisory until 9 AM PDT this morning for Mry Bay.
&&
$$
SHORT TERM...JM
LONG TERM....JM
AVIATION...Sarment
MARINE...Sarment
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, X, and YouTube at:
www.facebook.com/nwsbayarea
x.com/nwsbayarea
www.youtube.com/nwsbayarea
Prepared by Boulder-Creek.com Weather at: Wed Oct 7 04:30:03 PDT 2026
From the National Weather Service
|