783
FXUS66 KMTR 090359
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
859 PM PDT Fri Aug 8 2025

...New UPDATE, MARINE...

.KEY MESSAGES...
Updated at 228 PM PDT Fri Aug 8 2025

 - Moderate HeatRisk continues through Monday for portions of North,
   East, and South Bay counties and interior Monterey and San
   Benito counties.

 - Seasonally warm conditions through the early part of next week.

 - Elevated fire weather concerns persist given the warm and dry
   conditions, with breezy winds each afternoon and evening.

&&

.UPDATE...
Issued at 859 PM PDT Fri Aug 8 2025

Satellite imagery shows stratus right along the immediate coast
from Point Reyes southward, coming into the Monterey Bay region,
leaving out the city of Monterey itself, and just beginning to
travel south along the Salinas Valley. Webcams at the Half Moon
Bay airport are showing drizzle at the terminal, which forms the
basis for adding drizzle to the grids across the coastal regions for
the rest of the night. Otherwise, the main concerns continue to
be moderate HeatRisk in the interior Bay Area and Central Coast,
and the elevated fire danger risk across the region, which is
especially important considering that there have been a couple of
fires that did start today, one in the interior regions of Napa
County and another in the Santa Cruz Mountains.

DialH

&&

.SHORT TERM...
Issued at 232 PM PDT Fri Aug 8 2025
(This evening through Saturday)

Satellite imagery shows stratus set up along the immediate coastal
region from Point Reyes south to the Big Sur Coast. The weather
pattern is dominated by an upper level high pressure system moving
northwards in the eastern Pacific, bringing us warm temperatures
throughout the region, but especially inland, where high
temperatures rise as high as 5 to 12 degrees above seasonal
averages. High temperatures in the inland valleys today rise into
the 90s to as high as 103, while those close to the Bays reach into
the 70s to middle 50s, with the coastal areas hovering in the lower
to middle 60s. Highs tomorrow will be very similar to those seen
today. These high temperatures are causing moderate HeatRisk across
the inland portions of the Bay Area, Bayside regions of the
southeastern portions of San Mateo County and western Alameda
County, and portions of the inland Central Coast. This means that
there is a moderate risk for heat-related illnesses for populations
sensitive to heat, including children, the elderly, pregnant women,
people with certain chronic diseases, and people who work or live
outdoors without effective cooling or adequate hydration. Here are
some heat safety tips for people at risk for heat-related illnesses:

* 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.

While the heat will be the biggest weather impact to the region
through Saturday the marine layer isn`t going away. Therefore,
could see another round of drizzle and patchy dense fog along the
coast and locally inland tonight.

One other note is that with the Gifford Fire still active in San
Luis Obispo County, smoke from that fire may impact the southern
portions of Monterey and San Benito Counties through the evening
hours, with the bulk of the smoke plume pushing in to the Central
Valley and points east.

&&

.LONG TERM...
Issued at 232 PM PDT Fri Aug 8 2025
(Saturday night through next Thursday)

Finishing the weekend and starting off the work week - only minor
day to day changes in the overall sensible weather Sunday and
Monday. High pressure aloft is still the dominant weather
pattern...meaning more of the same. Night/Morning coastal marine
layer with afternoon inland heat. The temps/heat safety from the
short term are still value.

Still expecting relief to arrive by Tuesday and more so on
Wednesday as the ridge breaks down. Additionally, global
deterministic/ensembles have been showing a return of drizzle-
fest for Tuesday/Wednesday. Forecast has been update to include a
mention of coastal fog/drizzle.

What a temp roller coaster as the cooling really kicks in by
Thursday with many stations around the region 5 to 15 degrees
below seasonal averages. That means highs in the 60s to 80s - a
few 90s interior Central Coast. The cooldown is a result of the
weakening of the ridge, but more importantly the passage of a
trough through the Great Basin. This pattern can be a sign of
offshore flow.  For now we`ll just need to keep an eye on it.

&&

.AVIATION...
(00Z TAFS)
Issued at 445 PM PDT Fri Aug 8 2025

Stratus is expected to return tonight with a compressed marine layer
(~1000 ft depth) keeping it confined to the coastline. Highest
confidence in stratus impacting HAF, MRY, and SNS with GFSLAMP
guidance suggesting some potential for stratus to fill in over OAK
and portions of the SF Bay. Leaned more towards a persistence
forecast that stratus would not reach SFO or OAK tonight given the
relative stability of the marine layer around 1000 ft. Some
potential for fog overnight at HAF and MRY with CIGs and VIS to drop
early tomorrow morning. CIGs clear by mid to late morning with VFR
conditions persisting through the remainder of the afternoon.

Vicinity of SFO...VFR through the TAF period. Breezy northwesterly
winds continue into the evening hours before dissipating overnight.
Confidence is low that stratus will fill in over the SF Bay tonight
and reach OAK/SFO. Current thinking is that FEW to SCT clouds may
filter in over the SF Bay but the bulk of the stratus will be
confined to the coastline/offshore marine areas. If stratus does
reach SFO it is most likely to develop around 12Z and dissipate by
late tomorrow morning.

SFO Bridge Approach...Some potential for stratus to filter into the
SF Bay early tomorrow morning which may result in a loss of VAPs.
Any CIGs that do filter into the Bay will clear by late tomorrow
morning with VAPs through the remainder of the TAF period.

Monterey Bay Terminals...VFR becoming IFR-LIFR overnight. Satellite
shows a band of stratus just offshore with CIGs returning at MRY and
SNS by 04Z. Both CIGs and VIS will drop overnight with some
potential for fog at MRY early tomorrow morning (generally after
12Z). CIGs will clear by mid to late morning with VFR conditions
through the remainder of the TAF period. Diurnally breezy onshore
winds continue through the afternoon/evening hours before winds ease
and become locally variable overnight.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 843 PM PDT Fri Aug 8 2025

A fresh to strong northwesterly breeze will continue to diminish
across the far northern outer waters through tomorrow morning
becoming moderate to fresh by midday. Elsewhere, a gentle to
moderate northwesterly breeze and moderate seas will prevail
through  early next week. A strong breeze is expected to develop
across the  San Pablo Bay and delta region late tomorrow morning
through the  evening with gusts peaking around 25 knots.

&&

.FIRE WEATHER...
Issued at 920 AM PDT Fri Aug 8 2025

Solid nocturnal drying over the highest peaks last night. Chews
Ridge in the Santa Lucia range above Big Sur "recovered" early in
the night then steadily dropped below 20% by 4 AM. Needless to
say, areas like that would be consider poor on humidity recovery.
Thankfully, winds were not overly strong, just some low end gusts.

That being said, expect elevated fire weather concerns to persist
through Monday given interior heat, low humidity, and daily
afternoon wind gusts. Finer fuel/grass/veg fires seems most
likely.

MM

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from noon to 11 PM PDT Saturday for SF Bay
     N of Bay Bridge.

     Small Craft Advisory until 9 AM PDT Saturday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...DialH/MM
LONG TERM....MM
AVIATION...Kennedy
MARINE...Kennedy

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