Technical NOAA Weather Discussion

FXUS66 KMTR 122323
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
423 PM PDT Sun Apr 12 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1139 AM PDT Sun Apr 12 2026

 - Scattered rain showers with isolated thunderstorms will linger
   into midday on Monday

 - Gusty winds, especially at higher elevations Wednesday through
   Friday

 - A gradual warming and drying trend returns through the 
   remainder of extended forecast 

&&

.SHORT TERM...
Issued at 1139 AM PDT Sun Apr 12 2026
(This afternoon through Monday)

Scattered to numerous rain showers and isolated thunderstorms will 
remain possible throughout this evening. This is as the colder air 
mass aloft continues to provide enough instability in the post-
frontal environment. Now through early evening is when we have the 
greatest potential for convection as Surface Based CAPE remains 
between 200-700 J/kg across must of the region as a result of 
daytime heating. With the loss of daytime heating, the threat for 
thunderstorms will diminish and give way to mostly isolated to 
scattered rain showers, especially over the Pacific, Bay Area, and 
Central Coast. These rain showers may linger into midmorning on 
Monday as the mid/upper level low shift southward into southern 
California. 

Overnight temperatures will be chilly as winds diminish with mid-to-
upper 30s across the North Bay valleys and interior Central Coast 
(and higher elevations across the region). This may lead to frost 
formation the coldest, wind sheltered regions. However widespread 
frost is not likely. 

Monday will be up to 7 degrees F cooler than average (up to 20 
degrees F cooler in the higher elevations). Cloudy skies are 
anticpated to give way to mostly sunny skies by midday. However, 
fair weather cumulus will remain possible throughout the day over 
the higher terrain. 

&&

.LONG TERM...
Issued at 1139 AM PDT Sun Apr 12 2026
(Monday night through next Saturday)

Troughing will remain in place through Wednesday with temperatures 
warming slightly as high pressure nudges eastward over the eastern 
Pacific. By Wednesday, another mid/upper level through is forecast 
to drop down the British Columbia coast and into the Pacific 
Northwest. This will bring the potential for light rain to the North 
Bay with a 15-30% chance of precipitation by Wednesday afternoon and 
into Wednesday night. Little to no measurable rainfall is currently 
anticipated. Thus, we are not currently expecting any major impacts 
from this system as it slides into the Great Basin Thursday and into 
Friday. 

This will result in winds becoming offshore (northerly to 
northeasterly) across the North Bay Mountains and East Bay Hills 
Thursday afternoon and into Friday. Winds will also become offshore 
in other higher elevations across the Bay Area and Central Coast, 
however to a lesser extent. Again, fire weather concerns are not 
expected giving the decent wetting rainfall the region has 
experienced over the past several days. 

Forecast ensembles indicate a good probability of shortwave ridging 
building in across the eastern Pacific Friday and through the 
upcoming weekend. Thus, temperatures look to warm into the mid-to-
upper 60s near the coast and low-to-mid 70s across the interior.

&&

.AVIATION...
(00Z TAFS)
Issued at 422 PM PDT Sun Apr 12 2026

Isolated to scattered showers continue across the region, with the 
shower coverage expected to decrease after sunset and through the 
overnight hours through Monday midday. Flight categories will vary 
greatly with the remaining shower activity, generally VFR outside of 
showers with MVFR-IFR possible within them. Gusty southwest to west 
winds will also begin to diminish this evening into the overnight 
period. By Monday morning, shower activity will be highly isolated 
and a more moderate onshore flow will develop in the afternoon. 
There is a low confidence (around 10-20% probability) of fog 
developing in the interior valleys due to the recent rainfall. 
Confidence is too low to put this in the TAFs at this time.

Vicinity of SFO... Periodic shower activity continues through Monday 
midday at the very latest, with generally VFR conditions expect when 
showers pass over the terminal. Breezy southwest flow continues 
through the evening before winds shift to the northwest, diminishing 
overnight before resuming Monday afternoon.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... Low-level VFR to MVFR conditions expected 
through the TAF period with progressively diminishing shower 
coverage through the evening and overnight hours. Breezy southwest 
winds will diminish through the next few hours, with light drainage 
flow overnight before winds shift northwest for Monday afternoon.

&&

.MARINE...
(Tonight through next Friday)
Issued at 422 PM PDT Sun Apr 12 2026

Rain showers and isolated thunderstorms will gradually diminish
this  evening with lingering showers possible into early Monday
morning. A  moderate to fresh westerly breeze will prevail through
this evening  before veering to northwesterly overnight and
diminishing. Winds  continue to diminish and seas subside into the
early part of the  workweek, before winds increase and seas build
toward by Thursday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt 
     to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...DialH
MARINE...RGass/Navarrete

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Prepared by Boulder-Creek.com Weather at: Sun Apr 12 16:30:03 PDT 2026
From the National Weather Service