FXUS66 KMTR 311607
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
907 AM PDT Sat Oct 31 2026
...New UPDATE, MARINE...
.KEY MESSAGES...
Updated at 1030 PM PDT Fri Oct 30 2026
- Minor to moderate coastal flooding at high tide for Bayshore
and Pacific Coast locations through the weekend
- Seasonal to slightly below seasonal temperatures through the
extended forecast
- Potential for light rain Saturday and again next week
&&
.UPDATE...
Issued at 906 AM PDT Sat Oct 31 2026
Rain showers continue to diminish over the mountains of San
Bentio County and interior portions of Monterey County this
morning. However, these areas are where we have the best chance
for rain showers to continue throughout much of the day ahead of a
cold front that is forecast to sweep across the Bay Area later
this evening and then through the Central Coast overnight. As
mentioned in Short Term discussion, this is when we expect rain
chances to increase across the North Bay late this evening and
then across the rest of the Bay Area and Central Coast overnight.
No updates are anticipated to the ongoing forecast at this time.
RGass
&&
.SHORT TERM...
Issued at 1048 PM PDT Fri Oct 30 2026
(Tonight through Sunday)
Lots of talk about Saturday's sensible weather the last few days
and it's been a roller coaster. A few days ago it looked somewhat
wet for the Central Coast Saturday afternoon/evening. Then those
chances eased and actually shifted northward to the Bay Area/N
Bay. The latest forecast has actually eased precip chances
Saturday afternoon/evening everywhere in the CWA. In other words,
much more optimistic if you have any outdoor plans Saturday
afternoon/evening. Let's get into the details: the main weather
players for the short term continue to be an upper low drifting
slowly southward near the PacNW, an associated upper level trough
south of the low inch its way toward the West Coast, and a
moisture surge over the EPac (better surge heading into SoCal).
Over the next 12-24 hours, the upstream upper low drifts farther
south as the upper trough moves eastward and ultimately inland in
CA. At the surface, a weak offshore cold front will follow the
upper trough and move NW to SE Saturday afternoon/evening through
the region. For the Central Coast, they'll be on the northern
fringe of the SoCal surge so a few showers are possible during
the day across the far interior. Bay Area and North Bay start the
day dry and remain dry well into the afternoon and early evening.
There after, light rain chances increase over the North Bay
spreading southward Saturday night into Sunday. As the front moves
inland it begins to fade and so do the precip chances. A few
showers linger early Sunday, but Sunday afternoon looks much
drier. All in all, outdoor Halloween activities look promising
with only a few showers moving into the North Bay. Better precip
chances arrive Saturday night. Outside of precip chances,
temperatures this weekend look seasonably cold with highs mainly
in the 60s.
This is still valid - A combination of high astronomical tides
and surge from thermal expansion and low pressure 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 1.5 ft above normal (7.3 ft MLLW) at 3:44 PM, and
1.0 feet above normal (6.8 ft MLLW) at 3:59 PM Sunday, including
around 1.5 ft of surge residual." The Coastal Flood Advisory drops
off after high tide on Saturday for the Pacific Coast but remains
in effect through Sunday for bayshore locations along the San
Pablo, San Francisco, and Monterey Bays.
&&
.LONG TERM...
Issued at 1048 PM PDT Fri Oct 30 2026
(Sunday night through next Friday)
Weak upper level ridging Sunday night into Monday with dry weather
and slightly warmer temperatures. There after the forecast looks
unsettled with rain chances returning. The upper ridge moves
inland as another upper low approaches from the west. Next round
of rain returns Monday night into Tuesday and lingers into
Wednesday. By no means any big or notable storms, but precip
chances nonetheless through mid week. Dry weather and warmer
weather returns Friday and into next weekend.
&&
.AVIATION...
(12Z TAFS)
Issued at 433 AM PDT Sat Oct 31 2026
Currently VFR except LIFR at APC. High confidence in VFR and diurnal
winds prevailing through the afternoon. Moderate confidence on rain
showers tonight with the best chances between 05Z and 11Z. While the
trend has been slower, there is not great agreement on the location
and timing. Reasonable worst case scenario is they arrive earlier
with activity continuing through tomorrow morning. Reasonable
best case scenario is the column doesn't become saturated and thus
it doesn't rain. While ceilings are expected to remain VFR, they
will be low-end tonight. If a rain shower passes over a terminal,
brief reductions in ceilings and visibilities are expected.
Vicinity of SFO...Currently VFR and calm. High confidence in VFR and
westerly flow prevailing through this afternoon. Moderate confidence
on rain showers tonight which will be capable of briefly reducing
the ceiling and visibility.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Currently VFR with easterly flow at MRY and
VFR and calm at SNS. High confidence in VFR and diurnal winds
prevailing through the afternoon; however, low-end VFR ceilings will
likely prevail through the TAF period. Moderate confidence on rain
showers tonight which will be capable of briefly reducing the
ceiling and visibility.
&&
.MARINE...
(Today through Thursday)
Issued at 906 AM PDT Sat Oct 31 2026
Variable gentle to moderate breezes with moderate seas continue
into early next week. By mid-week, northwest moderate to fresh
winds are forecast with seas building to rough across the outer
waters. The chance for light rain showers tonight into Sunday
continue with another round possible Tuesday into Wednesday. A
long period southerly swell remains this weekend and combines with
a long period northwesterly swell on Monday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 6 PM PDT Sunday for CAZ006-506-508-
529-530.
Coastal Flood Advisory until 6 PM PDT this evening for CAZ505-
509.
PZ...None.
&&
$$
SHORT TERM...MM
LONG TERM....MM
AVIATION...Sarment
MARINE...Navarrete
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: Sat Oct 31 10:30:04 PDT 2026
From the National Weather Service
|