FXUS66 KMTR 221805
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1105 AM PDT Wed Jul 22 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1219 AM PDT Wed Jul 22 2026
- Breezy onshore winds return for the second half of the week
- Temperatures will hover around normal through the week
&&
.UPDATE...
Issued at 859 AM PDT Wed Jul 22 2026
Widespread drizzle and/or light rain fell over the past 12 hours
across the Santa Cruz and Watsonville region this morning with up
to 0.12" in the Santa Cruz Mountains around Bonny Doon. In Marin
County, Mount Tamalpais also picked up 0.12" as it is a favored
upslope region with the southwesterly winds. Isolated spots also
picked up a few hundredths of an inch in the East Bay Hills, Big
Sur coast, and coastal areas of Sonoma County. This is as the
marine layer has returned brining cooler temperatures to the
region today, yet mostly sunny skies are expected across the
interior by this afternoon.
RGass
&&
.SHORT TERM...
Issued at 148 AM PDT Wed Jul 22 2026
(Today and tonight)
Low clouds and the leading edge of cooler air on southwesterly
winds with the eastern side of the northward moving remnant low
(once part of tropical storm Elida) rapidly moved to and filled in
along the coast Tuesday afternoon and evening. The remnant low is
still enveloped by a tropical air mass, but it also has had time
to draw in cooler air into the circulation from the northwest.
This is the air that'll cool our temperatures today, but it'll
also feel muggy and damp today. There may even be a few patches of
light drizzle/light rain in the newly arriving moisture rich and
cooler air mass combination.
Since about 8 pm to 10 pm Tuesday, an increase in surface dewpoint
temperatures (higher water vapor) has spread across about the entire
forecast area. Dewpoint temperatures in the 50s and 60s are now
widespread.
An area of increasing larger scale subsidence and a clearing sky
coincided with maximum diurnal surface heating on Tuesday, boosting
daytime highs well above normal including breaking several record
high temperatures in our forecast area for July 21st. However,
other long term stations such as Santa Rosa, San Francisco, Napa,
Kentfield, San Jose and Livermore with a period of record back
including July 1917 were in the middle of a several day heat wave
this time in 1917; none of these stations reached record highs on
Tuesday.
Daytime highs today will be noticeably cooler even far inland:
60s/70s coastside to the 70s/80 bayside and 80s/90s far inland.
Lows in the 50s to lower 60s tonight.
&&
.LONG TERM...
Issued at 148 AM PDT Wed Jul 22 2026
(Thursday through Tuesday)
More typically drier (gradually less humid) summer weather
develops Thursday onward to the weekend, along with onshore
breezes, night and morning low clouds and fog and possibly
patchy drizzle. High pressure may compress the marine layer over
the weekend bringing a slight warming trend to inland areas.
The latest ECMWF and GFS show dry conditions in the 700-500 mb
layer, mostly if not entirely dominated by mid-latitude winds
over our forecast area for the next 10 days. Any daytime heating
potential instability will be capped by thermal and height ridging
at least out through 84 hours according to the 00z NAM model.
&&
.AVIATION...
(18Z TAFS)
Issued at 1039 AM PDT Wed Jul 22 2026
An onshore gradient and 1800 ft deep marine layer have kept cigs
in place over coastal terminals. Latest satellite imagery depicts
a rapidly eroding cloud deck over inland area while coastal
stratus persists. Winds remain out of the south to southwest and
will gradually veer back to west and NW through the day as the
clouds retreat back to the coast. Anticipate an early return to of
the marine layer this evening.
Vicinity of SFO...Moderate and occasionally gusty southerly winds
will prevail through the morning hours as marine layer hovers near
the terminal. Southerly wind have help keep the skies mostly MVFR
to IFR. Cigs are expected to make an early return as winds veer to
the northwest this afternoon.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...MVFR Cigs are expected to persist through
the remainder of the morning then temporarily scatter out in the
early afternoon before returning around sunset this evening.
&&
.MARINE...
(Today through Monday)
Issued at 1039 AM PDT Wed Jul 22 2026
A moderate southerly wind will gradually shift to NW through
Wednesday afternoon. Winds will increase to a fresh NW breeze
Thursday-Friday, with similar conditions continuing into next
week. Significant wave heights will remain moderate this week
before long period southerly swell from Hurricane Fausto reaches
the coastal waters this weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Thursday for Mry Bay.
Small Craft Advisory from 3 PM Thursday to 3 AM PDT Friday for
Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory from 9 AM Thursday to 3 AM PDT Friday for
Pigeon Pt to Pt Pinos 0-10 nm.
Small Craft Advisory from 9 PM this evening to 3 AM PDT Friday
for Pt Pinos to Pt Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...CW
MARINE...CW/Flynn
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Prepared by Boulder-Creek.com Weather at: Wed Jul 22 12:30:03 PDT 2026
From the National Weather Service
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