FXUS66 KMTR 300458
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
958 PM PDT Tue Sep 29 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1229 PM PDT Tue Sep 29 2026
- Elevated fire weather conditions across the higher terrain
through Wednesday
- Areas of moderate HeatRisk across the interior Wednesday
through Tuesday
- Minor coastal flooding near high tide for bayshore locations
along the San Francisco, San Pablo, and Monterey Bays today
through Thursday
&&
.SHORT TERM...
Issued at 1229 PM PDT Tue Sep 29 2026
(This evening through Wednesday night)
Isolated patches of stratus and fog linger along the coast, but the
region remains generally clear. With the marine layer compressing in
response to incoming ridging, any stratus development tonight is
limited to the coastal regions, with fog development possible along
the coast.
A pattern change is underway as ridging over the eastern Pacific
builds into the western United States, with temperatures warming
above to significantly above the seasonal averages (5 to 15 degrees
warmer) as a result. High temperatures today will be in the middle
80s to the middle 90s for the inland valleys, the middle 70s to the
middle 80s near the Bays, and the middle 60s to the lower 70s for
the Pacific coast. Wednesday's highs will be similar. A breezy
onshore flow should set up each afternoon and evening, while the
overnight and morning period will feature a push of offshore flow
across the interior mountains of the North and East Bay.
Beginning today and especially Wednesday, areas of Moderate HeatRisk
start to pop up across the inland regions. These correspond to a
moderate risk of heat-related illnesses for sensitive populations,
including children, the elderly, pregnant women, people with chronic
illnesses, and people who work or live outdoors without access to
adequate cooling or hydration. These areas are not widespread enough
to put out a Heat Advisory, but still impact several populated
regions, notably the interior valleys of the East Bay and the San
Jose region. Follow these tips to avoid heat exhaustion and
heatstroke:
* Stay hydrated and drink plenty of fluids.
* Wear lightweight, light-colored clothing.
* Reduce time spent outdoors or stay in the shade.
* Never leave people or pets unattended in vehicles.
* Use sunscreen if going to the coast or the pool.
Minor coastal flooding is possible across the bayshore locations of
San Francisco Bay, San Pablo Bay, and Monterey Bay around high tide.
Up to 1.2 feet of inundation above normally dry land is expected,
including up to 0.7 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 1.2 ft above
normal (7.01 ft MLLW) at 1:30 PM Tuesday 9/29 and 1.2 ft above
normal (7.03 ft MLLW) at 2:10 PM Wednesday 9/30.
&&
.LONG TERM...
Issued at 1229 PM PDT Tue Sep 29 2026
(Thursday through next Monday)
Little change in the sensible weather through the week as a rather
resilient ridge sets up across the western United States, supported
by the ensemble model cluster analysis and the ensemble model means
from the European, American, and Canadian ensemble models.
Temperatures may fluctuate a few degrees owing to fluctuations in
the upper level pattern, but for the most part, high temperatures
through the seven day outlook should be similar to today's highs.
The current forecast even suggests a few degrees of warming for the
upcoming weekend, with warm spots in the interior valleys reaching
the upper 90s and even some isolated triple digits. This is also
when we start to see more widespread areas of Moderate HeatRisk,
although it's a little early to put out a Heat Advisory. Longer
range outlooks suggest that temperatures above seasonal averages
will continue into the middle 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 1.1 ft above normal (6.92
ft MLLW) at 2:58 PM on Thursday 10/1.
&&
.AVIATION...
(06Z TAFS)
Issued at 954 PM PDT Tue Sep 29 2026
Currently VFR except MVFR at HAF. Moderate confidence on LIFR
conditions returning to the coastal terminals of HAF, MRY, and SNS
with lower confidence in the return at APC and STS, elsewhere VFR.
With stratus well offshore, this will likely be achieved via
radiational cooling. The best chances are between 08Z and 16Z,
more specifically when radiational cooling maximizes around
sunrise (14Z). Diurnal winds will prevail. Haze will reduce slant
range visibilities.
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 with southwesterly flow at
MRY and VFR with northerly flow at SNS. Moderate confidence on LIFR
conditions returning tonight, best chances are between 08Z and 16Z.
Diurnal winds will prevail.
&&
.MARINE...
(Tonight through next Monday)
Issued at 954 PM PDT Tue Sep 29 2026
Hazardous conditions for small craft will continue through
Wednesday night across the outer waters and coastal jet regions
of Point Reyes and Point Sur. Frequent northerly gale force gusts
will continue tonight across the northern outer waters.
Conditions will improve Thursday and into the weekend as
northerly breezes diminish to become gentle to moderate. Rough to
very rough seas Wednesday will subside to become moderate by
Friday.
&&
.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 Thursday for Pigeon Pt to Pt
Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory until 3 AM PDT Wednesday for Pt Pinos to Pt
Piedras Blancas 0-10 nm.
Gale Warning until 9 AM PDT Wednesday for Pt Arena to Pt Reyes
10-60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
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 Sep 30 00:30:03 PDT 2026
From the National Weather Service
|