FXUS66 KMTR 311830
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1130 AM PDT Sat Oct 31 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1129 AM PDT Sat Oct 31 2026
- Minor coastal flooding at high tide for Bayshore and Pacific
Coast locations through the weekend
- Seasonal to slightly below seasonal temperatures through Thursday
- Potential for light rain Saturday night and again early in the
upcoming week
&&
.SHORT TERM...
Issued at 1129 AM PDT Sat Oct 31 2026
(This afternoon through Sunday)
Chances for rain showers remain greatest (20-50%) across the
mountains of San Bentio County and interior portions of Monterey
County through the rest of the day today. This is all head of a
cold front that will approach from the northwest and move
southeastward across the North Bay late this evening (between 7 -
11 PM PDT), across the rest of the Bay Area (between 11 PM PDT - 6
AM Sunday PST), and across the Central Coast (between 1 - 7 AM
Sunday PST). As the front moves through the region overnight,
there is a 10-20% probability of thunderstorms, largely over the
coastal waters. Post frontal rain showers may linger offshore and
along the Monterey County coastline through early Sunday
afternoon. All in all, rainfall amounts are forecast to be on the
light side through Sunday afternoon with the greatest probability
of measuring >0.25" being in the coastal ranges and lesser amounts
as you move farther inland.
By Sunday afternoon, expect mostly dry and clearing sky
conditions as weak ridging builds in from the eastern Pacific in
wake of the exiting trough. Temperatures will remain seasonably
cool with afternoon highs in the 60s and overnight lows in the 40s
to lower 50s with the coldest regions of the North Bay
potentially reaching into the upper 30s both tonight and Sunday
night. Again, coastal flooding remains possible along the bayshore
locations of the San Francisco, San Pablo, and Monterey Bays
through Sunday at 6 PM PST with the Pacific Coast dropping off at
6 PM PDT this evening. For more information on that please see the
CFWMTR product.
&&
.LONG TERM...
Issued at 1129 AM PDT Sat Oct 31 2026
(Sunday night through next Friday)
The next chance for rain across the region will be from early
Tuesday morning through Wednesday morning as an upper level cut-
off low approaches the northern California coast from the west.
But again, not expecting widespread heavy rainfall from this
system. The placement of the cut-off low remains in question from
Monday night through Wednesday. A farther north track would result
in less rainfall across the Bay Area and Central Coast vs. a more
southern track. Dry weather now looks to return for the remainder
of next week with a gradual warming trend heading into next
weekend.
&&
.AVIATION...
(18Z TAFS)
Issued at 1111 AM PDT Sat Oct 31 2026
Breezy onshore winds this afternoon with VFR ceilings. Winds ease
this evening ahead of the first few rainbands. Light rain showers
are forecast to arrive between 11 PM PDT - 1 AM PST (06-08Z).
Ceilings may lower as the rain approaches the coast, remaining
mainly VFR with a chance of borderline VFR-MVFR decks. Impacts to
visibility are also possible. Overall, medium confidence on rain
impacts as this morning's 12Z KOAK sounding measured decreased
moisture content compared to yesterday with dry air confined to the
surface. Lower confidence on impacts at terminals in rain shadowed
areas, such as SJC and LVK. Dry, VFR conditions prevail through
Sunday morning with the potential for some lingering showers over
Monterey Bay.
Vicinity of SFO...VFR with high clouds cruising through. Onshore
winds increase this afternoon and ease in the evening. Moderate
confidence for light rain showers to arrive at the terminals around
midnight with lower VFR ceilings and slight visibility reductions.
If rain develops overnight, expect improved conditions by Sunday
morning with increasing moderate northwesterly breezes.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR as onshore winds increase this
afternoon. Winds ease and shift southerly as light rain showers
approach the terminals. If the rain materializes, borderline MVFR-
VFR ceilings and visibility reductions are possible overnight with
conditions improving by late Sunday morning.
&&
.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...RGass
LONG TERM....RGass
AVIATION...Navarrete
MARINE...Navarrete
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Prepared by Boulder-Creek.com Weather at: Sat Oct 31 14:30:03 PDT 2026
From the National Weather Service
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