FXUS66 KMTR 290704
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1204 AM PDT Thu Oct 29 2026

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

.KEY MESSAGES...
Updated at 1203 AM PDT Thu Oct 29 2026

 - Moderate coastal flooding at high tide for Bayshore and Pacific
   Coast locations through Friday and Saturday

 - Seasonal to slightly below seasonal temperatures through the
   extended forecast

 - Potential for rain this weekend and again early to mid next
   week

&&

.SHORT TERM...
Issued at 1203 AM PDT Thu Oct 29 2026
(Today and tonight)

Satellite imagery shows high clouds across the region, the byproduct 
of a decaying upper level low from the west that is merging into the 
troughing pattern across the West Coast. Cloudy conditions will 
likely persist through the day today as morning lows hover in the 
lower to middle 40s in the inland valleys and the upper 40s to the 
lower 50s closer to the coasts, while highs remain in the upper 60s 
to the lower 70s in the inland valleys and the SF Bayshore and the 
lower to middle 60s along the Pacific coast. Winds will generally 
remain light and gentle with some breeziness in the afternoon and 
evening hours in favored locations.

Now to address the elephant in the room. Several high-resolution 
models, including the HRRR and the experimental RRFS, are showing 
some simulated reflectivity returns coming in later this morning and 
continuing through the day across the region, but especially focused 
on the South Bay and the Central Coast. On the surface it seems like 
rain should be in the forecast, but other meteorological analysis 
comes in and says "Not so fast!". Looking at the 00Z (5 PM PDT) 
sounding from Oakland reveals a deep layer of very dry air 
stretching from the 850 mb layer to the 500 mb layer where dew 
points range from around -30 to -50 degrees Centigrade. That is a 
three-mile thick column of air that any potential precipitation will 
have to overcome for rain to develop, and whether we'll get anything 
making it to the surface depends on whether developing cells can 
overcome that dry layer. The current forecast leans towards "no" 
with anything seen on KMUX radar today evaporating before it reaches 
the ground, or virga. We can't dismiss the possibility of rain 
completely, but it looks to be something that at most brings a few 
sprinkles or hundredths of an inch of rain to the mountaintops over 
something that would be more impactful.

A combination of high astronomical tides and surge from thermal 
expansion effects brings the risk of minor coastal flooding along 
the Bayshore at the San Pablo, San Francisco, and Monterey Bays, and 
the Pacific coast, at high tide today. At the San Francisco tidal 
gauge, high tide is expected to be 1.9 ft above normal (7.7 ft MLLW) 
at 01:43 PM  Thursday 10/29, including around 1.2 ft of surge 
residual partially attributed to impacts from El Nino.

&&

.LONG TERM...
Issued at 1203 AM PDT Thu Oct 29 2026
(Friday through Wednesday)

High temperatures in the inland valleys will fluctuate in the middle 
60s to the lower 70s through the seven day outlook. Large scale 
troughing remains in place through the next couple days before 
chances for rain come into the region later on Saturday into Sunday. 
As the trough starts to push its way eastwards into the West Coast, 
a upper level jet streak will take aim at the central and southern 
portions of California. This will facilitate cyclogenesis and a 
developing surface low takes aim at southern California and the 
northern portions of Baja California. Those regions will see the 
bulk of the rain from this system, but the fringes of the moisture 
will come into the Central Coast and will likely give the interior 
measurable rain, if not much rain. Forecast rain totals are still 
fluctuating, but the interior portions of Monterey and San Benito 
Counties should see around a tenth to a third of an inch of rain 
Saturday into early Sunday. Elsewhere, light showers are possible 
within the Monterey Bay region and even extending into the South 
Bay, especially if the parent system takes a more northerly track.

A progressive ridge will come into the region Sunday into Monday 
before another system comes in towards the end of the seven-day 
outlook. Last time I had stated that the speed and track of that 
incoming system was highly uncertain. That remains the case judging 
from the ensemble model cluster analysis and even just looking at 
various model outputs heading into the middle of next week. The 
current forecast retains the rain chances for the end of the seven-
day outlook, but by necessity they are low (10-30% probability) and 
the certainty in any further detail is lower still.

Coastal flooding concerns continue across Bayshore locations within 
the San Pablo, San Francisco, and Monterey Bays through Saturday and 
the Pacific coastal regions through Friday. At the San Francisco 
tidal gauge, high tide is expected to be 1.6 ft above normal (7.4 ft 
MLLW) at 02:39  PM Friday 10/30, and 1.1 feet above normal (6.9 ft 
MLLW) at 03:44 PM on Saturday 10/31, including around 1.2 ft of 
surge residual partially attributed to impacts from El Nino.

&&

.AVIATION...
(06Z TAFS)
Issued at 839 PM PDT Wed Oct 28 2026

Winds will become light and variable then light offshore tonight 
and Thursday morning. Surface high pressure over far northern 
California and the Great Basin will weaken by later Thursday. High
and mid level clouds will increase tonight and Thursday, reducing
radiative cooling tonight and radiative warming Thursday. VFR is 
forecast in the 06z TAFs.

Vicinity of SFO...VFR. West wind 5 to 10 knots decreasing to 
light west to northwest wind then shifting to light northeast 
Thursday morning. West to northwest wind 10 knots Thursday 
afternoon and early evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Light and variable winds then light
east to southeast winds tonight and Thursday morning. West to 
northwest winds near 10 knots Thursday afternoon and early 
evening. 

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 837 PM PDT Wed Oct 28 2026

Moderate to strong northwest winds continue into the night across
the outer waters with fresh to moderate breezes along coastal
waters, with seas continuing to build in response and resulting in
rough seas over exposed waters. Expect gradually improving
conditions by Thursday and into the early part of the weekend. A
long period west-northwest swell is forecast to arrive late this
weekend and into early next week.

&&

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

     Coastal Flood Advisory until 5 PM PDT Friday for CAZ505-509.

PZ...Small Craft Advisory until 9 PM PDT this evening for Pt Arena to 
     Pt Reyes 10-60 NM.

     Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt 
     to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Canepa

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Prepared by Boulder-Creek.com Weather at: Thu Oct 29 04:30:04 PDT 2026