FXUS66 KMTR 291929
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1229 PM PDT Tue Sep 29 2026
...New SHORT TERM, LONG TERM...
.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 MHHW) at 1:30 PM Tuesday 9/29 and 1.2 ft above
normal (7.03 ft MHHW) 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 MHHW) at 2:58 PM on Thursday 10/1.
&&
.AVIATION...
(18Z TAFS)
Issued at 1033 AM PDT Tue Sep 29 2026
Most terminals were VFR this morning under clear skies, but
Monterey Bay region and N Bay Valleys had dense fog leading to
LIFR conditions. Since then, VFR have developed and will continue
through this afternoon. Gusty onshore winds possible for SFO and
OAK this afternoon. For tonight another night of mostly VFR most
terminals. However, a shallow/compressed marine layer will allow
for periods of LIFR conditions - same locations N Bay and
Monterey Bay region. Conf is 30% for dense fog. Conditions may
ebb and flow so included dense fog as tempo group.
Vicinity of SFO...VFR. Gusty onshore this afternoon up to 20 kt.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR this afternoon. Lower CIGs return
tonight with LIFR conditions possible tomorrow AM due to dense
fog.
&&
.MARINE...
(Today through Sunday)
Issued at 1033 AM PDT Tue Sep 29 2026
Strong high pressure off the California Coast will result in fresh
to near gale northerly breezes through Wednesday over the coastal
waters. Frequent gale force gusts are expected across the
northern waters through Wednesday morning. Conditions will begin
to improve Wednesday night as northerly breezes diminish to become
gentle to moderate, with locally hazardous conditions across the
northern outer waters likely to continue. Rough to very rough seas
through Wednesday will subside to become moderate to rough.
&&
.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 PM PDT this afternoon for Pt Arena
to Pt Reyes 0-10 nm.
Gale Warning until 9 PM PDT this evening for Pt Arena to Pt
Reyes 0-10 nm.
Small Craft Advisory until 3 AM PDT Wednesday for Pigeon Pt to
Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt
Reyes to Pigeon Pt 0-10 nm.
Gale Warning until 9 AM PDT Wednesday for Pt Arena to Pt Reyes
10-60 NM.
Small Craft Advisory until 3 PM PDT Wednesday for Pigeon Pt to
Pt Pinos 10-60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...MM
MARINE...MM
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: Tue Sep 29 14:30:03 PDT 2026
From the National Weather Service
|