FXUS66 KMTR 131135
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
435 AM PDT Sun Sep 13 2026
...New AVIATION, MARINE, FIRE WEATHER...
.KEY MESSAGES...
Updated at 1022 PM PDT Sat Sep 12 2026
- Breezy onshore winds persist through Sunday afternoon
- Temperatures near seasonal averages through the upcoming week
- Dry offshore winds for the higher terrain Sunday night into
Monday night
&&
.SHORT TERM...
Issued at 1022 PM PDT Sat Sep 12 2026
(Tonight through Sunday)
Skies are generally clear, save for the Pacific coast of San Mateo
County where some low clouds have developed overnight, and will
generally remain so through the day on Sunday. There is a low
confidence of stratus development near the northern end of the Santa
Lucias that could impact the southern Monterey Bay region early
Sunday morning, but if this develops it should mix out soon after
dawn.
The weather pattern remains dominated by a cutoff low coming into
Oregon, which interacts with a broad area of zonal flow and slight
ridging across the Southwest to create a strong pressure gradient
over the northern half of California and Nevada. At 9 PM the SFO-WMC
gradient was measured at 9.7 mb, and there are still a couple of
hours where the gradient could strengthen further before the cutoff
low's motion starts to relax the gradient. Wind gusts across the
region have peaked at around 20 to 35 mph, with the most favored
locations seeing wind gusts of over 50 mph. This is expected to
continue well into the night, with some abatement in the early
morning hours on Sunday. By the time the sea breeze kicks in Sunday
afternoon, the pressure gradients will relax, but remain rather
strong and some elevated winds are still possible before the winds
finally turn light in the late evening hours. Widespread gusts will
likely reach 20 to 30 mph with favored locations along the coast and
through gaps, passes, and valleys reaching 40 mph.
Morning lows will generally hover in the upper 40s to the 50s
across the region. Sunday's highs range from the middle 70s to the
lower 80s inland, the middle 80s in the warmest reaches of
southern Monterey County, the middle 60s to the middle 70s near
the Bays, and the lower to middle 60s close to the Pacific coast.
&&
.LONG TERM...
Issued at 1022 PM PDT Sat Sep 12 2026
(Monday through next Saturday)
The trough axis continues moving into the northern Plains by Monday,
relaxing the pressure gradients and diminishing the potential for
strong winds. Some troughing influence will remain along the West
Coast through at least the middle of the week and there may even be
a pulse of energy coming off the back of the first trough that would
reinforce the pattern, keeping temperatures near to below seasonal
averages. High temperatures will range across the 80s inland, the
lower 70s to the lower 80s close to the bays, and the middle 60s to
the lower 70s near the Pacific coast. The widespread marine layer
stratus deck should return Monday night into Tuesday, and will
develop each night and morning before mixing out through the
afternoon hours. Friday into the upcoming weekend, model ensembles
are showing a chance for some sort of ridge influence across the
region, thus reflecting the probability for a slight warming
trend.
&&
.AVIATION...
(12Z TAFS)
Issued at 435 AM PDT Sun Sep 13 2026
It's VFR except for patchy coastal stratus /MVFR/. Diurnal warming
will mix out patchy stratus with VFR prevailing across the forecast
area late morning through afternoon. A few patches of coastal stratus
/MVFR-IFR/ redevelop tonight and Monday morning.
Vicinity of SFO...Tempo BKN MVFR ceiling until 15z this morning
otherwise VFR. West wind 10 to 20 knots increasing to 20 to 30
knots from late morning to mid evening. West wind 10 knots tonight
becoming light northeasterly early Monday.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Patchy morning stratus /MVFR-IFR/ nearby
KMRY and KSNS otherwise VFR today. Patchy stratus /MVFR-IFR/
redevelops tonight and Monday morning. Mainly onshore winds 5 to
10 knots except areas of gusts to 20 to 25 knots this afternoon
and early evening.
&&
.MARINE...
(Today through Friday)
Issued at 422 AM PDT Sun Sep 13 2026
Hazardous conditions for small craft prevail through the middle of
the week. Northwest winds strengthen today and tonight with gale
force gusts across the southern inner coastal waters and the
Monterey Bay. A few gale force gusts are possible across the
northern inner coastal waters. Winds will remain elevated through
midweek before decreasing late week. Moderate seas will build to
between 8 and 10 feet and become rough by Monday in response to
the stronger winds.
&&
.FIRE WEATHER...
Issued at 422 AM PDT Sun Sep 13 2026
Patchy coastal stratus has developed overnight. 925 mb relative
humidities are higher over the Timber and Plaskett fires early
this morning. Tonight into Monday night, a light to gentle
offshore breeze (with occasionally moderate gusts) is forecast to
develop in the higher terrain as the mid/upper level trough axis
shifts into the northern Rockies. As such, areas above the marine
layer often experience nocturnal drying that will likely continue
through early this upcoming week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this
evening for SF Bay N of Bay Bridge.
Small Craft Advisory until 3 PM PDT this afternoon for Mry Bay-
Pigeon Pt to Pt Pinos 0-10 nm.
Gale Warning from 3 PM this afternoon to 9 PM PDT this evening
for Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm.
Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt
Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory from 3 PM to 9 PM PDT Monday for Pt Arena
to Pt Reyes 0-10 nm.
Gale Warning until 9 PM PDT this evening for Pt Pinos to Pt
Piedras Blancas 0-10 nm.
Small Craft Advisory from 3 PM this afternoon to 9 PM PDT Monday
for Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory until 9 PM PDT Monday for Pigeon Pt to Pt
Pinos 10-60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Canepa
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Prepared by Boulder-Creek.com Weather at: Sun Sep 13 08:30:03 PDT 2026
From the National Weather Service
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