FXUS66 KMTR 282311
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
411 PM PDT Mon Sep 28 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1205 PM PDT Mon Sep 28 2026
- Elevated fire weather conditions across the higher terrain
through Wednesday
- Areas of moderate HeatRisk across the interior Wednesday
through Sunday
- Minor coastal flooding for bayshore locations along the San
Francisco, San Pablo, and Monterey Bays today through Friday
&&
.SHORT TERM...
Issued at 1205 PM PDT Mon Sep 28 2026
(This evening through Tuesday night)
The stratus has largely cleared out with some isolated patches
continuing at the immediate coast. Probability of stratus
development tonight is low to very low, as incoming ridging and
offshore flow will generally disrupt the marine layer stratus
formation processes.
The latest water vapor imagery shows an upper level low tracking
across the southern Central Valley into the Mojave Desert, expected
to continue trekking southeastward through the day and entering
Arizona by Tuesday morning. Behind the low, an incoming ridge
kickstarts a warming trend that will extend through the next couple
of days. Today's high temperatures range from the middle 70s to
middle 80s inland to the upper 60s to middle 70s along the Bays and
the lower to middle 60s at the Pacific coast. On Tuesday, high
temperatures will reach the middle 80s to middle 90s inland, the
middle 70s to middle 80s along the Bays, and the middle 60s to lower
70s at the Pacific coast.
With the northerly flow aloft as the upper level low moves towards
the southeast, a push of offshore wind is expected in the higher
elevations Tuesday morning. Gusts of 25 to 35 mph are expected along
the exposed ridgelines, and stronger gusts are possible along the
ridge of the Vaca Mountains along the Napa-Yolo and Napa-Solano
county lines. Elsewhere, generally diurnal winds will prevail with
onshore winds developing each afternoon and evening, with gusts to
30 mph along the coast, through favored gaps and passes, and within
the Salinas Valley.
Minor coastal flooding is possible across the bayshore locations of
San Francisco Bay, San Pablo Bay, and Monterey Bay around high tide
starting today. Up to 1.2 feet of inundation above normally dry land
is expected, including up to 0.6 ft of surge caused by thermal
expansion and sea level rise since the sea level datum (basically
the point where we define as "sea level") was set in the 1983-2001
period. At the San Francisco tidal gauge, high tide is expected
to be 1.0 ft above normal (6.87 ft MLLW) at 12:57 PM Monday 9/28
and 1.2 ft above normal (7.01 ft MHHW) at 1:30 PM Tuesday 9/29.
&&
.LONG TERM...
Issued at 1205 PM PDT Mon Sep 28 2026
(Wednesday through next Sunday)
There is an additional push of higher elevation offshore flow on
Wednesday morning. This push will be more focused on the interior
mountains of the North and East Bay with gusts a little lighter than
those expected on Tuesday morning. Otherwise, temperatures may
fluctuate by a few degrees each day, most notably on Thursday when
stronger onshore flow will cause some of the coastal regions to dip
by a few degrees, but the general trend should remain similar to
Tuesday's highs through the end of the seven day outlook. Areas of
Moderate HeatRisk, a level of heat that brings a moderate risk of
heat-related illnesses to sensitive populations, develop across the
interior regions Wednesday through Saturday, but confidence in
widespread impacts is not high enough to issue a Heat Advisory at
this point. Longer-range guidance suggests that temperatures above
the seasonal average will continue into the second week of October.
Minor coastal flooding around high tide continues in low-lying areas
across the San Francisco, San Pablo, and Monterey Bay shorelines
through Thursday and potentially into Friday. At the San Francisco
tidal gauge, high tide is expected to be 1.2 ft above normal (7.03
ft MHHW) at 2:10 PM Wednesday 9/30, and 1.1 ft above normal (6.92 ft
MHHW) at 2:58 PM on Thursday 10/1.
&&
.AVIATION...
(00Z TAFS)
Issued at 410 PM PDT Mon Sep 28 2026
VFR conditions prevail across most of the region through the night
and into Tuesday, with some MVFR-IFR ceilings possible overnight at
the immediate coast and particularly near Monterey Bay. A moderate
onshore wind continues through the evening hours, diminishing
overnight before gentle to moderate onshore winds resumes Tuesday
afternoon.
Vicinity of SFO... VFR through the TAF period. Breezy northwest
winds with strong gusts continue into the late evening hours,
diminishing overnight before resuming Tuesday afternoon.
SFO Bridge Approach... Similar to SFO
Monterey Bay Terminals... Patchy stratus lingers at the immediate
coast and has just come over MRY. Lower confidence in stratus
development at SNS; kept the terminal VFR through the night. Stratus
will mix out to the immediate coast Tuesday morning. A moderate
onshore wind continues through the evening hours, with light
drainage flow overnight before onshore winds resume Tuesday
afternoon.
&&
.MARINE...
(Tonight through next Saturday)
Issued at 410 PM PDT Mon Sep 28 2026
A strengthening pressure gradient along the California Coast will
keep moderate to strong northerly breezes through Wednesday.
Strongest winds will be the outer waters north of Point Reyes and
along the Big Sur Coast. Rough seas will accompany the winds and
will subside to moderate by the end of the week. Tropical
activity will produce long period swell up to 16 seconds Wednesday
and Thursday.
&&
.FIRE WEATHER...
Issued at 515 AM PDT Mon Sep 28 2026
The marine layer persists this morning, around 1500-2000ft, but
should gradually compress to around 500ft throughout the day.
Today will be coolest day of the week, though it is also the start
of a warming trend. Offshore flow gradually works its way into the
region today, which will lead to breezy winds each morning from through
Wednesday. The strongest winds are expected on Tuesday morning in
the interior mountains of the North and East Bays, where wind
gusts could reach 30-35 mph. These offshore winds should
contribute to poor overnight humidity recoveries, with overnight
relative humidities as low as 20-40% above the marine layer.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 5 PM PDT Thursday for CAZ006-506-
508-529-530.
PZ...Small Craft Advisory until 3 AM PDT Wednesday for Pt Arena to Pt
Reyes 0-10 nm.
Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt
to Pt Pinos 0-10 nm.
Small Craft Advisory until 11 PM PDT this evening for Pt Pinos
to Pt Piedras Blancas 0-10 nm.
Small Craft Advisory until 3 PM PDT Wednesday for Pigeon Pt to
Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...DialH
MARINE...MM
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Prepared by Boulder-Creek.com Weather at: Mon Sep 28 16:30:03 PDT 2026
From the National Weather Service
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