FXUS66 KMTR 020004
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
504 PM PDT Thu Oct 1 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1224 PM PDT Thu Oct 1 2026

 - Warm to hot temperatures through the next seven days

 - Hazardous heat for most inland locations this weekend

 - Mild overnight lows in the higher elevations will limit recovery

 - Minor coastal flooding at high tide for bayshore locations on
   the San Francisco, San Pablo, and Monterey Bays through Friday

&&

.SHORT TERM...
Issued at 1224 PM PDT Thu Oct 1 2026
(This evening through Friday night)

Ridging, ridging, ridging... a basic summary of the weather pattern 
across the western United States in the short and medium terms. We 
are in the middle of an extended period of temperatures warmer than 
seasonal averages and rather compressed marine layers, meaning that 
the stratus deck will remain confined to the immediate coast during 
the daytime and expand into the North Bay Valleys, the SF and 
Monterey Bay regions, and the northern Salinas Valley overnight, but 
keep the interior valleys generally clear. High temperatures today 
and Friday range from the middle 80s to middle 90s inland, the upper 
90s across the warmest spots of the interior Central Coast, the 
middle 70s to middle 80s near the Bays, and the middle 60s to lower 
70s at the Pacific coast. The onshore breeze will be rather light 
with gusts of 20 to 25 mph possible through favored gaps and passes 
and the northern Salinas Valley in the afternoon and evening hours. 

Regions of Moderate HeatRisk are expanding across the inland regions 
today and Friday. These correspond to a moderate risk of heat-
related illnesses for sensitive populations, including children, the 
elderly, pregnant women, people with chronic illnesses, and people 
who work or live outdoors without access to adequate cooling or 
hydration. Follow these tips to avoid heat exhaustion and heatstroke:

* 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.

Minor coastal flooding is possible across the bayshore locations of 
San Francisco Bay, San Pablo Bay, and Monterey Bay around high tide. 
Up to 1.1 feet of inundation above normally dry land is expected, 
including up to 0.7 ft of surge caused by thermal expansion and sea 
level rise since the sea level datum (basically the point where we 
define as "sea level") was set in the 1983-2001 period. At the San 
Francisco tidal gauge, high tide is expected to be 1.1 ft above 
normal (6.92 ft MLLW) at 2:58 PM on Thursday 10/1 and 0.9 ft above 
normal (6.71 ft MLLW) at 3:58 PM on Friday 10/2.

&&

.LONG TERM...
Issued at 1224 PM PDT Thu Oct 1 2026
(Saturday through next Wednesday)

As the upper level ridge starts to amplify over the western United 
States, a noticeable warmup this weekend will cause inland highs to 
rise into the middle 90s to near 103, while the Bays see highs 
across the 80s to the lower 90s, creating hazardous heat conditions 
for anyone without adequate cooling or hydration. Mild overnight 
lows in the upper 60s to middle 70s across the higher elevations and 
the middle to upper 60s in the interior East and South Bays will 
limit the opportunity for the body to recover overnight. As a 
result, a Heat Advisory has been issued from 11 AM Saturday to 10 PM 
Sunday across the Sonoma Coastal Range, the North Bay Interior 
Mountains, the San Francisco Bay Shoreline, the East Bay and South 
Bay, the Santa Cruz Mountains, the Santa Lucia Range, the interior 
mountains of Monterey and San Benito Counties, and the southern 
Salinas Valley. Meanwhile, locations along the Pacific Coast will 
feel the influence of a highly compressed marine layer, with highs 
in the upper 60s to middle 70s and lows in the upper 50s to lower 
60s. 

Towards the beginning of the next work week, the ridge begins to 
flatten and temperatures may cool by a couple of degrees, but 
chances for hazardous heat remain high and the Heat Advisory may A 
slight cooling of a couple of degrees at most is possible towards 
the next work week as the ridge begins to flatten, but need to be 
extended as the forecast comes into better view. Ensemble model 
cluster analysis converges on another amplification of the ridge 
towards the later part of the next work week, and things get 
interesting again for the second weekend of October (the 10th and 
11th). The clusters begin to split into scenarios that keep the 
ridging in place over the western United States and those that show 
more zonal flow or even a trough coming into the West Coast. This 
split between the cluster scenarios will be interesting to look at 
through the week, and is part of the reason why forecasts beyond the 
next seven days are more often discussed in terms of probabilities 
than deterministic language. 

&&

.AVIATION...
(00Z TAFS)
Issued at 446 PM PDT Thu Oct 1 2026

The marine layer is less than 1,000 feet deep with robust stratus
coverage along the coast. These clouds will push inland overnight,
bringing IFR-LIFR ceilings and visibility impacts to all but the
most inland terminals. The onset and clearing timing will be 
broadly similar to yesterday. High clouds are approaching and will
hang on through the majority of the TAF period.

Vicinity of SFO...Onshore winds are gusting into the mid 20s, but
will start to gradually calm down as the sun gets lower. The
stratus timing is a little uncertain. Boundary layer averaged
winds are out of the SW, which gives the terminal good protection,
even if OAK gets a ceiling much earlier in the night. Still, there
is a 60% chance of IFR impacts from 10Z through 16Z.

SFO Bridge Approach...No issues at the moment, but this is the
type of set-up where the approach gets ceilings earlier in the
evening than the terminal.

Monterey Bay Terminals...The ceilings are making an early push,
and SNS already has IFR ceilings. MRY probably has a couple hours
of VFR conditions left with SW wind, but it's basically a
guarantee for IFR or LIFR conditions through the night and the
frist half of the morning at both terminals. 

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 446 PM PDT Thu Oct 1 2026

Northerly gentle to moderate breezes will allow seas to steadily
abate to moderate by Friday. Marine conditions improve Friday into
early next week.

&&

.FIRE WEATHER...
Issued at 1224 PM PDT Thu Oct 1 2026

Persistent ridging across the western United States leaves the
interior hot and dry with poor to very poor daytime humidity 
retention away from the immediate coast, while a compressed marine
layer leaves overnight humidity recoveries poor across the higher
elevations. Hot daytime temperatures and mild overnight lows in
the thermal belts pose hazards for fire crews working in high
elevation areas, particularly within the Timber Fire where Major
to Extreme HeatRisk is possible during the weekend. In
addition, the hot and dry conditions lead to rising ERC values
with values in the North Bay and interior Central Coast expected
to reach the 90th to 97th percentile next week. 

DialH

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 6 PM PDT Friday for CAZ006-506-508-
     529-530.

     Heat Advisory from 11 AM Saturday to 10 PM PDT Sunday for CAZ503-
     504-508-510-512>518.

PZ...None.
&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Flynn
MARINE...RGass

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Prepared by Boulder-Creek.com Weather at: Thu Oct 1 20:30:03 PDT 2026