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 12:30:03 PDT 2026