FXUS66 KMTR 190447
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
947 PM PDT Sat Apr 18 2026
...New SHORT TERM, LONG TERM, AVIATION, MARINE...
.KEY MESSAGES...
Updated at 935 PM PDT Sat Apr 18 2026
- Seasonally warm temperatures Sunday
- Cooler temperatures, beneficial rainfall, and isolated
thunderstorms expected Monday through Wednesday
&&
.SHORT TERM...
Issued at 935 PM PDT Sat Apr 18 2026
(Tonight through Monday)
Satellite imagery shows high clouds continuing to cover the Bay Area
and Central Coast tonight, which are expected to continue to push
through the region in the overnight period before steadily thinning
and scattering Sunday morning. Low temperatures tonight are expected
to hover in the middle 40s to lower 50s across the region, perhaps a
few degrees warmer than the current forecast if the high level cloud
cover is enough to inhibit radiational cooling and reflect thermal
energy back to the surface.
Today will be a day of temperatures close to the seasonal averages,
with the inland valleys reaching highs in the 70s, the Bays seeing
highs in the middle 60s to lower 70s, and the Pacific coast hovering
around the upper 50s to the lower 60s. A gentle onshore breeze with
a southwesterly component will develop during the afternoon, with
the breezy winds persisting into the night as a cold front
approaches the region.
&&
.LONG TERM...
Issued at 935 PM PDT Sat Apr 18 2026
(Monday night through next Saturday)
The focus of the seven-day outlook continues to be centered around
the cold front coming through the Bay Area and Central Coast for the
early part of the work week. Pre-frontal rain showers are expected
to arrive sometime Monday morning across the North Bay and continue
to spread southward through the day, with the main frontal band
coming through later on Monday into Tuesday morning. Behind the
front, and with the associated upper level low coming through
northern California, the newly arrived cold pool will allow for a
chance of isolated to scattered thunderstorms through Tuesday
afternoon and evening, with probabilities ranging from around 20 to
30 percent across the region. Lingering showers and chances for
isolated thunderstorms (up to 15% probability) continue through
Wednesday, and should move out of the region by Wednesday night.
Through all of this, high temperatures will dip into the lower to
middle 60s in the lower elevations to the 50s across the higher
elevations, and rain totals will range from 0.5-1.5" across the
interior valleys and most of the Bay Area and Monterey Bay regions,
to around 1.5-3" in the coastal ranges and the interior mountains of
the North Bay. This should be mostly beneficial across the region,
but some minor nuisance flooding is possible in urban and poor
drainage areas if heavy rain showers or thunderstorms develop.
As the frontal system passes, temperatures will warm slightly into a
rather dry latter part of the week, back to around the seasonal
averages rather similar to today's highs. Extended guidance from the
Climate Prediction Center leans towards temperatures and rain
totals above seasonal averages for the last week of April.
&&
.AVIATION...
(06Z TAFS)
Issued at 935 PM PDT Sat Apr 18 2026
Broken to overcast high clouds continue and will persist through
the TAF period. A slow moving cold front over the Eastern Pacific
will gradually slide towards the coast over the next couple days.
This will gradually shift winds to a southerly direction and
eventually bring some rain and widespread mid-level ceilings. In
the meantime there is a decent chance for marine layer stratus to
creep in overnight, particularly at STS, HAF, MRY and SNS. While
not in the TAF explicitly, SFO, OAK, and SJC have a slight chance
of a sunrise stratus surprise as well.
Vicinity of SFO...IFR ceilings just formed at HAF, but they will
likely struggle to cross the Peninsula overnight. That being said,
there is 20-30% chance of MVFR ceilings between 13-17Z. As the
cold front approaches, winds will tend to be just south of west
Sunday afternoon, rather than the typical WNW.
SFO Bridge Approach...Persistent high clouds similar to SFO.
Monterey Bay Terminals...The southern terminals have the best
chance for ceiling impacts Sunday morning with more low level
moisture already in place.
&&
.MARINE...
(Tonight through next Friday)
Issued at 935 PM PDT Sat Apr 18 2026
A slow moving cold front will approach the coast through Monday,
gradually flipping the wind direction southerly over the next 24
hours before increasing to a fresh breeze Sunday night through
Monday as some rain moves in. After the front passes, the
associated low pressure system will move through the coastal
waters, bringing a slight chance for thunderstorms on Tuesday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 3 PM PDT Monday for Mry Bay-
Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras
Blancas 0-10 nm.
Small Craft Advisory from 3 AM to 3 PM PDT Monday for Pigeon Pt
to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Flynn
MARINE...Flynn
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Prepared by Boulder-Creek.com Weather at: Sat Apr 18 22:30:02 PDT 2026
From the National Weather Service
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