FXUS66 KMTR 181904
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1204 PM PDT Sat Apr 18 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1201 PM PDT Sat Apr 18 2026
- Seasonably warm temperatures expected through the remainder of
the weekend
- Cooler temperatures and beneficial rain for the beginning of
the upcoming week
&&
.SHORT TERM...
Issued at 1201 PM PDT Sat Apr 18 2026
(This evening through Sunday)
High clouds continue to stream in from the west, yet will have very
little impact on high temperatures this afternoon. We are
forecasting mid 60s to lower 70s in the northwest facing locations
and low-to-upper 70s elsewhere. There is a greater than 50%
probability for Concord, San Jose, Gilroy, Hollister, and King City
to exceed 80 degrees F on this afternoon (but less than 10% of
exceeding 85 degrees F).
Tonight and into Sunday morning, expecting low clouds to return to
the coast and coastal adjacent valleys as moisture increases ahead
of an approaching mid/upper level low. This low will also cool
temperatures slightly as clouds increase, most notability in the
North Bay and San Francisco Bay Area. Meanwhile, the Central Coast
will remain quite warm across the interior Sunday afternoon.
&&
.LONG TERM...
Issued at 1201 PM PDT Sat Apr 18 2026
(Sunday night through next Friday)
The progression of the anticipated cold front has slowed down by
about 12-18 hours. However, we still expect pre-frontal rain showers
to begin Monday morning across the North Bay and then spread
southward across the Bay Area. Outside of the coastal ranges of the
Central Coast, we may see very little rainfall on during the day
Monday. The main cold front is now expected to move across the Bay
Area and Central Coast on Tuesday morning. By Tuesday afternoon and
evening, we have the greatest potential for thunderstorms with up to
30% across much of the region as up to 500 J/kg of surface based
CAPE is forecast. We are mostly forecasting this rainfall to be
beneficial, but urban and poorly drained areas may experience
flooding concerns during periods of heavy rain showers and/or
thunderstorms. The WPC has a Marginal Risk of Excessive Rainfall (at
least 5%) from the Santa Cruz Mountains northward on Day 3 (5 AM
Monday - 5 AM Tuesday). However, we are not expecting any major
river flooding with this event.
Post-frontal rain showers and possible thunderstorms (generally less
than 15%) linger into Wednesday afternoon as a colder air mass
settles in behind the cold front. Drier conditions look to return to
the region for the latter half of the week with troughing forecast
by the clusters.
&&
.AVIATION...
(18Z TAFS)
Issued at 1100 AM PDT Sat Apr 18 2026
High clouds are building across the area with moderate winds
building into the afternoon. Winds become light into the evening and
into the night with low clouds building along the coast. IFR CIGs
look to affect HAF and and the Monterey Bay terminals overnight and
through much of Sunday morning. Winds stay light for most areas
through Sunday morning, but moderate southwest winds begin to build
that afternoon.
Vicinity of SFO...VFR through the TAF period. High clouds will build
through the day and into Sunday. Expect west-northwest winds to
build through the afternoon but ease into the late night. Winds stay
light through early Sunday afternoon before moderate west-southwest
winds build.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR lasts into the the night. Expect
moderate northwest winds to build into the afternoon and ease into
the late evening. IFR CIGs build at MRY and around the Monterey Bay
coastline into the night, but don't reach SNS until the late night.
Winds will stay light through Sunday morning, but CIGs will erode in
the mid to late morning.
&&
.MARINE...
(Today through Thursday)
Issued at 1100 AM PDT Sat Apr 18 2026
Light winds and seas last through the rest of the weekend.
Northerly winds shift and become southerly Sunday ahead of an
incoming low pressure system and cold front. Winds will strengthen
ahead of the cold front Monday through Tuesday with localized
strong gusts expected. Expect moderate seas, rain and a slight
chance to chance of thunderstorms Monday night and Tuesday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Murdock
MARINE...Murdock
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Prepared by Boulder-Creek.com Weather at: Sat Apr 18 16:30:02 PDT 2026
From the National Weather Service
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