Technical NOAA Weather Discussion

FXUS66 KMTR 012009
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
109 PM PDT Tue Sep 1 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 107 PM PDT Tue Sep 1 2026

 - Cooler weather continues through the week

 - Beneficial wetting rain expected in the North Bay through 
   Thursday

&&

.SHORT TERM...
Issued at 107 PM PDT Tue Sep 1 2026
(This evening through Wednesday night)

Mostly clear sky conditions have returned to the Central Coast 
with scattered low clouds across the Bay Area and North Bay. There
are also high clouds associated with an approaching frontal 
boundary across the North Bay. As such, temperatures today will be
5-15 degrees below normal as the 850 mb temperature drops below 
10C/50F for the first time since May. Additionally, there is a 
chance for for light rain and/or drizzle across the North Bay 
tonight into Wednesday morning with pre-fronatal coastal drizzle 
for areas to the south. 

Low clouds will spread back inland overnight and into Wednesday 
morning with temperatures generally the 50s across much of the 
region and in the 40s in the higher elevations. Similar conditions
are forecast for Wednesday with another disturbance moving in 
from the northwest Wednesday night into Thursday. This will bring 
increasing potential for light rain across the North Bay and 
portions of the Bay Area. The greatest potential to see greater 
than 0.25" will be in the coastal ranges of the North Bay and 
0.10" in and around Santa Rosa and the Sonoma County valleys by 
Thursday morning. Rainfall amounts drastically drop off the 
further south you go. 

&&

.LONG TERM...
Issued at 107 PM PDT Tue Sep 1 2026
(Thursday through next Monday)

Heading into this upcoming weekend, there is the potential we see a 
slight warming trend high pressure over the central United States 
builds westward. However, troughing off of the West Coast will main 
cooler than average temperatures throughout the weekend. 

Ensemble clusters diverge heading into next week. As such, still 
keeping an eye on tropical development over the eastern Pacific 
Ocean for any northward movement of tropical moisture. However, 
the latest guidance is indicating the track of TS Marie should 
stay well to our south, potentially bringing impacts to southern 
California. For more information on tropical developments visit 
nhc.noaa.gov. 

&&

.AVIATION...
(18Z TAFS)
Issued at 1006 AM PDT Tue Sep 1 2026

VFR conditions are expected to prevail through the forecast period
for all terminals. A deepening trough will continue to mix out
lingering low level clouds by early afternoon.

Vicinity of SFO...VFR with occasionally breezy onshore flow this
afternoon and early evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR is expected to prevail through the
forecast period with a slight chance of MVFR ceilings developing
after midnight.

&&

.MARINE...
(Today through Sunday)
Issued at 915 AM PDT Tue Sep 1 2026

Light northwesterly breezes will persist through the week with
occasional moderate breezes. Slight to moderate wind driven seas
will continue through the week with tropical cyclone activity
producing long period southerly swell by the end of the week into
the weekend.

&&

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

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...JM
MARINE...JM

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 1 14:30:03 PDT 2026
From the National Weather Service