776
FXUS66 KMTR 310830
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
130 AM PDT Sun Aug 31 2025

...New SHORT TERM, LONG TERM, FIRE WEATHER...

.KEY MESSAGES...
Updated at 129 AM PDT Sun Aug 31 2025

 - Moderate risk for heat-related illnesses today and Monday

 - Elevated fire weather concerns across the interior mountains
   into Monday with low RH and moderate onshore winds each
   afternoon

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

&&

.SHORT TERM...
Issued at 129 AM PDT Sun Aug 31 2025
(Today and tonight)

Mostly clear skies will persist today and tonight. A drier airmass
combined with a compressed marine layer will result in spotty
stratus development confined to only the coastline, if there is any
at all. Temperatures will increase slightly for many locations this
afternoon from Saturdays highs. A Heat Advisory is not warranted,
but people visiting any of the numerous inland and elevated
recreational areas in our forecast area should be aware of the warm
temperatures and plan accordingly. Stay hydrated, seek shade, take
breaks and dont leave people or pets in vehicles. Breezy onshore
flow this afternoon will also result in elevated fire weather
concerns, see below for more information.

&&

.LONG TERM...
Issued at 129 AM PDT Sun Aug 31 2025
(Monday through Saturday)

A weak upper level low continues to gradually approach from
offshore. The weak disturbance will draw in improved mid-level
moisture between H50-H70. We will continue monitor the non-zero
chance for elevated convection Monday into Tuesday. As the upper
level disturbance approaches the coast, it is likely to evolve into
a negatively tilted open wave. As of right now, the best lift is out
of phase and north of the improving mid-level moisture that is
expected to be in place, however subtle changes in the timing and
position of the disturbance could lead to increasing chances of
elevated thunderstorms. Lightning and gusty winds would be the
primary concern. Beyond Tuesday, the moderate heat begins to ease
through mid-week, with notable cooling by the end of the week into
next weekend.

&&

.AVIATION...
(06Z TAFS)
Issued at 939 PM PDT Sat Aug 30 2025

Currently VFR at all terminals with high clouds beginning to filter
in from a low pressure system over the Eastern Pacific Ocean. High
confidence in VFR through the TAF period as the pattern will change
very little from the previous 24 hours. As the region remains under
the influence of the upper-level shortwave ridge, stagnant, sinking
air will facilitate an environment where haze and smoke from nearby
wildfires will not be able to mix out. As such, expect reduced slant
range visibilities.

Vicinity of SFO...Currently VFR with northwesterly flow. High
confidence in VFR and westerly flow prevailing through the TAF
period.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently VFR and calm at MRY and VFR with
northwesterly flow at SNS. High confidence on VFR and onshore flow
prevailing through the TAF period.

&&

.MARINE...
(Tonight through next Friday)
Issued at 939 PM PDT Sat Aug 30 2025

Fresh to strong northwesterly breezes will prevail through the
weekend with strong gusts and thus hazardous conditions for small
craft across much of the waters. Moderate to fresh northwesterly
breezes will prevail Monday through Wednesday. Moderate seas will
prevail through Wednesday.

&&

.FIRE WEATHER...
Issued at 129 AM PDT Sun Aug 31 2025

Warm and dry conditions will continue today and Monday, especially
for locations above 500ft. Widespread MinRH values between 10%-20%
combined with occasional wind gusts up to 30 MPH will result in
elevated fire weather concerns. We are also monitoring the potential
for elevated thunderstorms Monday afternoon into Tuesday. Chances
are low at the moment, but if the pattern evolves with improved
timing of the mid-level moisture and best lift associated with the
upper level disturbance we could see some isolated convection across
portions of the Bay Area, East Bay Hills and North Bay.

&&

.BEACHES...
Issued at 939 PM PDT Sat Aug 30 2025

A Beach Hazards Statement is in effect through 11PM Monday due to
long period (18 seconds) southwesterly swell causing an increased
risk for sneaker waves and rip currents along southwest facing
beaches, including but not limited to: Stinson Beach, Santa Cruz
Boardwalk Beach, and Twin Lakes Beach. Sneaker waves can
unexpectedly run significantly farther up the beach than normal,
including over rocks and jetties. Rip currents are typically more
frequent and stronger in the vicinity of jetties, inlets, and piers.
It is always important, but especially so on a warm, dry, holiday
weekend, to exercise caution while at the beach. Never turn your
back on the ocean, remain out of the water to avoid hazardous
swimming conditions, keep pets on a leash, and wear a life jacket.

Sarment

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Monday evening for CAZ505-509-
     529.

PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this
     evening for Mry Bay.

     Small Craft Advisory until 9 PM PDT Monday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Monday
     for Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 AM PDT Monday for Pigeon Pt to Pt
     Pinos 0-10 nm.

     Small Craft Advisory until 9 AM PDT Monday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 AM PDT Tuesday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...Sarment
MARINE...Sarment

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