Weather Service Report


974 
FXUS66 KMTR 070246
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
746 PM PDT Sun Jul 6 2025

...New UPDATE...

.KEY MESSAGES...
Updated at 129 PM PDT Sun Jul 6 2025

 - Moderate HeatRisk returns to portions of the Interior Bay Area
   and Central Coast Wednesday through next weekend.

 - Localized elevated fire weather conditions for the Bay Area and
   Central Coast Wednesday through next weekend.

 - Slight risk (20%-40%) of extreme heat for far interior portions
   of the Bay Area and Central Coast July 12th-14th.

&&

.UPDATE...
Issued at 715 PM PDT Sun Jul 6 2025

The marine layer stratus is beginning its nocturnal push inland 
as the sun begins to set. By morning, the coverage should be 
slightly more expansive than today as low pressure offshore 
allows the marine layer to deepen. Cool and moist will be the 
theme through Tuesday before a ridge builds and brings inland 
temperatures above normal Wed-Fri. Thursday looks like the warmest
day, but with temperatures about 5 degrees above normal, we are 
only expecting moderate HeatRisk in inland and higher elevation 
areas within the North Bay, East Bay, South Bay and Monterey and 
San Benito Counties. A cooling trend should bring temps back to 
normal this weekend.

&&

.SHORT TERM...
Issued at 129 PM PDT Sun Jul 6 2025
(This evening through Tuesday)

An upper-level cutoff low off the Northern California Coast will be 
the defining feature of the short term forecast. Sensible weather 
will feature seasonably cool conditions and onshore winds with gusts 
up to 35 mph through gaps and passes, across ridgelines, and down 
the Salinas Valley. The marine layer is currently being observed at 
1,800 feet on the Fort Ord profiler and will continue to deepen to 
3,000 feet by Tuesday. This, in addition to the stratus presentation 
currently, means that it will have no problem penetrating farther 
inland tonight and continuing that trend tomorrow night. There is 
also a slight (15%) chance for drizzle along the coast and over the 
waters due to the lifting mechanism in place. Southerly transport 
winds may (you guessed it) transport smoke in from the Madre Fire 
that is burning in San Luis Obispo through Tuesday.

&&

.LONG TERM...
Issued at 129 PM PDT Sun Jul 6 2025
(Wednesday through next Saturday)

The pattern begins to change Wednesday as the upper-level cutoff low 
becomes an open wave and gets nudged eastward by building broad high 
pressure. This will kickoff the warming and drying trend with the 
return of moderate HeatRisk and localized elevated fire weather 
conditions. Fortunately, several rounds of upper-level shortwave 
trough energy will help keep the ridge in check, not allowing the 
axis or peak to enter our area. Global ensemble clusters are in 
agreement with heights rising through Thursday with the ridge 
showing signs of weakening, albeit slightly, Friday. This will 
translate to Thursday being the warmest day of the week with 
temperatures topping out at 10 degrees above normal with Friday 
being slightly cooler. Global ensemble clusters diverge Saturday 
with 51% in favor of heights rebuilding and 49% in favor of heights 
falling, suggesting uncertainty in the forecast. The propagation 
of what happens will be integral in the extended forecast as the 
Climate Prediction Center (CPC) has highlighted the far interior 
portions of the Bay Area and Central Coast with a slight (20%-40%)
chance of extreme heat July 12th-14th, thus it is intuitive to 
believe that if the ridge has more time to build that we could be 
dealing with hotter conditions and subsequently greater impacts 
than what are currently being forecast. In terms of elevated fire 
weather conditions, high pressure and the accompanying subsidence 
aloft will compress the marine layer to 1,000 feet Wednesday 
resulting in little inland intrusion and poor to moderate relative
humidity recovery above it. Additionally, light offshore flow is 
expected in the higher terrain during the morning hours of 
Wednesday and Thursday. Please exercise fire and heat safety, 
especially coming off of a cool June.

&&

.AVIATION...
(00Z TAFS)
Issued at 446 PM PDT Sun Jul 6 2025

High confidence for an early return of stratus tonight filling 
into the coastal valleys and lowering early Monday morning. Low 
clouds that do develop by Monday morning will likely scatter out 
and/or clear by Monday afternoon, with the exception of immediate
coastal locations.

Vicinity of SFO...Medium confidence for MVFR ceilings to return 
late tonight and potentially lowering to IFR at times early Monday
morning. Stratus is forecast to scatter out between 16Z-17Z 
Monday morning giving way to VFR through the afternoon

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...High confidence for IFR/MVFR ceilings to
return this evening and lower to LIFR at times early Monday 
morning. Also high confidence in clearing to VFR at more inland
sites like KSNS, but lower confidence along the coast and around
KMRY.

&&

.MARINE...
(Today through Friday)
Issued at 1048 AM PDT Sun Jul 6 2025

Fresh northwesterly breezes will continue today for the outer
waters and coastal jet regions of Point Reyes and Point Sur. Winds
gradually begin to slack Monday with moderate to fresh breezes
forecast through Wednesday with a surface low positioned over the
outer waters. Northwesterly winds increase and significant wave
heights build beginning late in the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...Behringer
MARINE...RGass

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Western Regional Climate Center, wrcc@dri.edu