370
FXUS66 KMTR 300439
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
939 PM PDT Fri Aug 29 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 1256 PM PDT Fri Aug 29 2025

 - Temperatures near seasonal averages today, warming for the
   weekend through the middle of next week

 - Elevated fire weather concerns across the interior mountains
   this weekend with low RH and moderate onshore winds in the
   afternoons

 - Hazardous coastal conditions Saturday through Monday night due
   to long period southerly swell

&&

.UPDATE...
Issued at 859 PM PDT Fri Aug 29 2025

Our forecast area remains on the western periphery of a strong
500 mb (593 decameters) high pressure system centered over West
Texas and Northern Mexico. A high pressure ridge extends across
AZ, NV, OR and WA to Western Canada. This high pressure system is
within a long wave ridge that`s forecast to slowly edge northward
(northward moving highs strengthen, depth of troposphere decreases)
and retrograde (westward moving). The 500 mb height on the Oakland
upper air sounding was 587 decameters which is about typical for
late August. The large scale synoptic pattern over the eastern
Pacific and western states is essentially stuck and slightly
retrogressive as mentioned. The 500 mb pattern across the CONUS
will become amplified through next week, favoring hot weather
west, cool/chilly weather east. In our forecast area daytime highs
Saturday-Tuesday will become a few degrees hotter than today,
best chance of this will be inland away from afternoon and evening
sea breezes.

In September-October we typically will see offshore winds, hotter
and dry (an extension of the summer dry season) conditions, but
the good news is outside of an occasional moderate strengthening
of the ACV-SFO pressure gradient (northerly wind) there`s at least
currently not any strong signal of offshore winds anytime soon.
This is because of the sluggish synoptic pattern described is not
favorable for it, but of course we need to keep a close eye on it
this time of year. The global models have recently shown there has
been at least some difficulty for the forecast models to keep up
with the evolving hemispheric pattern, at least the portion covering
the northeastern Pacific. Forecast solutions have been generally
diverging after about 120 hours or ~ 5 days out. For additional
info on the forecast please see the discussions below.

&&

.SHORT TERM...
Issued at 1256 PM PDT Fri Aug 29 2025
(This evening through Saturday)

Stratus has cleared inland with temperatures this afternoon forecast
to warm into the upper 80s to lower 90s across the interior and in
the higher elevations, upper 60s to lower 80s just inland away from
the coast, and 60s to lower 70s near the coast/bays. Breezy onshore
winds are forecast to develop this afternoon and continue into the
evening with gusts of 25 to 35 mph in the favored gaps and passes,
Salinas Valley, and along the coast and in higher elevations.

Tonight, temperatures will cool into the 50s for most urban areas,
lower 60s across the interior valleys, and the 70s to lower 80s in
the higher terrain. Low clouds are also forecast to return inland
early Saturday morning and will dissipate by late morning. This will
bring increased humidity to lower elevations overnight, yet dry
conditions prevail in the higher elevations.

For Saturday, temperatures will warm by a few degrees with
temperatures forecast to be in the low 90s to near 100 degrees F
across the interior and in the higher elevations, low 70s to mid 80s
just inland away from the coast, and upper 60s to mid 80s near the
coast/bays. These temperatures will be 5-15 degrees F above average
for this time of year. This will result in isolated to scattered
Moderate HeatRisk across interior areas.

&&

.LONG TERM...
Issued at 1256 PM PDT Fri Aug 29 2025
(Saturday night through next Thursday)

Temperatures will hold steady as far as maximum/minimum temperatures
go through the remainder of the weekend and into early next week. As
such, Moderate HeatRisk will persist through at least through mid-
week of the upcoming week. We will need to keep an eye on the need
for any Heat products as we move into the upcoming week.

From previous forecaster: "This level of heat will bring a risk of
heat-related illnesses to vulnerable populations, including
children, the elderly, pregnant women, and people who are working or
living outdoors without adequate shelter or hydration. Near the
coasts, a compressed marine layer should retain the ability to keep
temperatures from rising dramatically, but areas that will lose the
marine layer influence, including much of the Bay Area, could see
temperatures jump 5 to 10 degrees. The heat will also contribute to
some elevated fire weather conditions across the interior mountains.
More information is available in the FIRE WEATHER section."

&&

.AVIATION...
(06Z TAFS)
Issued at 939 PM PDT Fri Aug 29 2025

VFR continues at the terminals, however coastal stratus and fog
/MVFR-IFR-LIFR/ will redevelop tonight and Saturday morning.
Slightly warmer lower level temperatures in the marine layer
temperature inversion is forecast tonight and Saturday. Stratus
and fog will mix out by late Saturday morning. Onshore winds will
prevail locally gusty during the afternoon and evening.

Vicinity of SFO...VFR except tempo stratus MVFR 12z-16z Saturday.
West wind near 10 knots tonight and Saturday morning then increasing
to near 30 knots Saturday afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR continuing into the evening, stratus
and fog /IFR/ then developing tonight and Saturday morning. Stratus
and fog mixing out by late Saturday morning otherwise VFR. Winds
mainly onshore 5 to 15 knots.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 857 PM PDT Fri Aug 29 2025

Fresh to strong wind gusts are developing and look to last
through the holiday weekend along with increasing wave heights.
The gusty winds and choppy seas will create hazardous conditions
across our coastal waters through the weekend into the beginning
of the next work week.

&&

.FIRE WEATHER...
Issued at 312 PM PDT Fri Aug 29 2025

Warming and drying trend under way into this weekend as high
pressure builds aloft. Marine layer compression has begun this
afternoon with some areas showing as low 800-900 feet. Daytime
humidities will still be moderate-to-high below this elevation.
However, elevations above about 1,000 feet will see RH in the
teens during the afternoons through the weekend and into next
week. While we aren`t anticipated any long-duration wind events,
we do expect breezy NW winds to develop each afternoon during
peak heating, especially favoring gaps and passes in the East Bay
interior mountains. The energy release component (ERC) of
available fuels is showing slightly above average (higher burn
potential) for most locations across the region, with the most
notable being the North Bay zones which are forecasted to be well
above average for this time of year. Also, a fun tidbit worth
noting; we are right around our climatological peak for fuel
energy release component. Learn more about ERCs at
https://gacc.nifc.gov/oscc/fuelsFireDanger.php

Behringer

&&

.BEACHES...
Issued at 125 PM PDT Fri Aug 29 2025

Long-period (15-18 seconds) south-southwest swell originating from
previous Tropical Storm Juliette will impact the coast Saturday
through Monday night, creating an elevated risk for sneaker waves,
rip currents, and rough surf. This will be especially so at
southwest facing beaches including but not limited to Stinson
Beach, Santa Cruz Boardwalk Beach and Twin Lakes Beach. The
potential exposure to the dangers will be enhanced by the Labor Day
holiday weekend as folks flock to the coast to escape the hot inland
temperatures across the interior.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from 5 AM PDT Saturday through Monday
     evening for CAZ505-509-529.

PZ...Small Craft Advisory from 9 AM Saturday to 3 AM PDT Sunday for
     Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory from 3 PM Saturday to 3 AM PDT Sunday for
     Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60
     NM-Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory until 3 AM PDT Sunday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Canepa
MARINE...Canepa

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