FXUS66 KMTR 172343
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
343 PM PST Wed Dec 17 2025
...New AVIATION...
.KEY MESSAGES...
Updated at 304 AM PST Wed Dec 17 2025
- Mostly dry for tonight and Thursday with the exception of
coastal drizzle tonight into early Thursday morning.
- Patchy to Areas of dense fog likely overnight
- Rain, wind, and general thunderstorms Sunday
- Rainy and windy conditions are expected to continue through the
holiday into the end of next week
&&
.SHORT TERM...
Issued at 226 PM PST Wed Dec 17 2025
(This evening through Thursday)
A mix of sun and clouds for the remainder of the afternoon in the
wake of a relatively weak cold front that pushed through our area
earlier this morning. Rainfall received overnight and this morning
was beneficial with most low lying areas seeing around a tenth-of-an-
inch, and higher elevations seeing from a tenth-of-an-inch to half-
an-inch. Expect areas of dense fog to develop overnight within
inland valleys. especially the North Bay, Bay Area and East Bay.
Closer to the coast, fog and drizzle will combine to limit
visibility overnight into early Thursday morning.
Thursday will be mostly dry with the exception of the coastal
drizzle that should taper off an hour or two after sunrise.
Thursdays high temperatures will be right around normal, slightly
above normal for higher elevations within the Central Coast. The
first wave of numerous rounds of rainfall will first move into the
North Bay late in the day Thursday with only light rain for the
onset into Friday.
&&
.LONG TERM...
Issued at 226 PM PST Wed Dec 17 2025
(Thursday night through next Tuesday)
Plenty of uncertainty remains with the exact timing and intensity of
the rainfall we're expecting to impact our area beginning Friday
through the remainder of the extended forecast. What we do know attm
is the North Bay will see the most rainfall as several waves of
moderate/heavy rainfall push through over the next week, along with
elevated coastal ranges from San Mateo south through the Santa Cruz
mountains into the Santa Lucia's. The period of heaviest rainfall as
of this writing looks to be late Saturday night through early Monday
morning, which means Sunday may be difficult travel day. Give
yourself plenty of extra time to travel at anytime over the next
week, but especially Sunday.
The totals over the coastal ranges will standout on ours and others
weather maps you'll see as we head into one of the busiest travel
times of the year. However, low lying areas all across our region
will see plenty of impacts from the rain, wind and other cumulative
problems associated with multiple storm systems moving over our
area. By the beginning of next week we are likely to see rivers
begin to swell and the potential for rock and land slides to
interfere with travel plans. Signals for rainfall chances beyond the
scope of our official forecast persist into the end of next week as
well.
Most of the Pacific Coast is highlighted in CPC outlooks for
excessive rainfall through the extended forecast. Please monitor
our web page (weather.gov/mtr) for updated rainfall total maps,
more specific timing and impacts for our area along with our
partners at the CPC for bigger picture products across the West
Coast (cpc.ncep.noaa.gov).
&&
.AVIATION...
(00Z TAFS)
Issued at 332 PM PST Wed Dec 17 2025
Generally MVFR-VFR with mid-to high level ceilings across the
region. A light to gentle onshore flow prevails through the evening
hours with light winds overnight, with onshore winds returning
Thursday afternoon. The clearing trend will continue through the
rest of the afternoon and evening hours with generally MVFR-IFR
stratus developing overnight across the Bay Area valleys and the
southern Salinas Valley. Chances for rain begin to enter the North
Bay Thursday morning, but best chances for STS do not arrive until
after the end of the 24-hour TAF period.
Vicinity of SFO... VFR conditions with SCT low clouds continue
through the evening hours with breezy west-northwest winds becoming
light overnight. MVFR stratus returns to the terminal around
midnight with a gradual diminishing to IFR conditions through the
pre-dawn hours. Clearing is expected late Thursday morning, with a
return to breezy west-northwest winds in the afternoon. Stratus
returns late Thursday evening in advance of a rain band expected to
arrive after the end of the TAF period.
SFO Bridge Approach... Similar to SFO.
Monterey Bay Terminals... VFR conditions with breezy northwest winds
continue through the afternoon. MVFR-IFR stratus returns in the late
evening with shallow fog development possible due to the clear
skies. VFR conditions return late Thursday morning with the return
of breezy northeast winds.
&&
.MARINE...
(Tonight through next Monday)
Issued at 226 PM PST Wed Dec 17 2025
Light to moderate onshore breezes will prevail with moderate seas
through late week. Rain chances return to the northern waters on
Thursday night and will push southward through the day on Friday.
Additional rain arrives Saturday night and will continue off and
on at times through much of next week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
SHORT TERM...JM
LONG TERM....JM
AVIATION...DialH
MARINE...RGass
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Prepared by Boulder-Creek.com Weather at: Wed Dec 17 16:30:02 PST 2025
From the National Weather Service
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