Saint Helena, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

311
FXUS66 KMTR 100947
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
247 AM PDT Tue Jun 10 2025

...New SYNOPSIS, SHORT TERM, LONG TERM, MARINE...

.SYNOPSIS...
Issued at 238 AM PDT Tue Jun 10 2025

A slight cooling trend starts today for the more interior areas
Otherwise expect a continuation the daily patter of marine layer
clouds each night and morning, some coastal drizzle, a few
pockets of fog, and breezy onshore winds each afternoon and
evening.

&&

.SHORT TERM...
(Today and tonight)
Issued at 238 AM PDT Tue Jun 10 2025

The overnight forecasting team did some extra polishing into the
short term forecast. The fog/drizzle/ and cloud cover forecast have
been finely tuned and adjusted as the marine layer continues to
dominate the coast and the slightly inland. Patches of fog will favor
the North Bay valleys as well as the coast through the late morning.
Brief moments of drizzle will also be possible along the immediate
coast and around the Monterey Bay. So fairly similar morning
conditions as the last few days, but the pattern does begin to
change today.



The slight ridge pattern is turning into a more zonal upper level
pattern.

What does that mean? I`m glad you asked.

It means the upper level environment will start moving to a more
direct west to east flow over the west coast, leading to more
onshore flow. It also means today will be cooler for the more
interior areas that haven`t been seeing those strong pushes of low
level clouds from the marine environment. Don`t expect it to be a
robust cool-down, as most of the interior areas are only seeing a
few degrees difference.

For areas along the coast and affected by the marine layer, don`t
expect much in the way of change. A cloudy morning, with some
clearing in the afternoon and then back to cloudy in the evening.
It`s very much the summer stratus pattern giving the "June Gloom."
The change to zonal flow will expand the marine layer, allowing it
to flow deeper inland, but looks to reduce the concentration of
moisture within the marine layer, allowing for some areas to see
cloud cover to clear sooner.

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 238 AM PDT Tue Jun 10 2025


The upper-level pattern will continue to promote onshore flow well
into the long term forecast. This will continue the cooling trend
for the more interior areas, as well as the cloudy coastal and
valley conditions. A weak trough looks to move through the area over
the weekend, allowing the marine layer expansion to continue. This
will result in the cloud layer levels rising through weekend, and
less chances for fog. After that, the longer term models are
struggling to figure out what to do with the post-trough
environment. Some models are hinting at a quick transition into a
ridge pattern in the middle of the next work week, leading to
another warming trend, while others stay more zonal, which keeps our
current trend. This will be something worth checking back in as the
forecast continues to develop!

&&

.AVIATION...
(06Z TAFS)
Issued at 957 PM PDT Mon Jun 9 2025

Onshore winds supported by a 4.1 mb SFO-SAC pressure gradient
will continue to usher stratus /MVFR-LIFR/ inland tonight and
Tuesday morning. Patchy light drizzle is possible as well. Stratus
mixing out back to near the immediate coastline Tuesday afternoon
then stratus moves inland Tuesday night and early Wednesday.

Vicinity of SFO...Stratus /IFR/ tonight and Tuesday morning.
Stratus mixing out to scattered clouds /VFR/ Tuesday afternoon
then stratus /MVFR-IFR/ moving inland Tuesday evening and night.
West wind near 10 knots tonight and Tuesday morning. West wind
gusting to 25 knots Tuesday afternoon to mid evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus /MVFR-IFR/ and patchy light
drizzle tonight and Tuesday morning. Stratus lifting to MVFR-VFR
by late Tuesday morning or early afternoon, stratus /MVFR-IFR/
returns Tuesday evening and night. Mainly onshore winds 5 to 15
knots, with a few higher gusts to 20 knots during the afternoon.

&&

.MARINE...
(Today through Sunday)
Issued at 238 AM PDT Tue Jun 10 2025

Fresh to strong northwesterly breezes will prevail through the
forecast period with gale force gusts possible beginning Wednesday
afternoon along the coastal jet regions of Point Reyes and Point
Sur. Significant wave heights will be moderate today, building to
become rough tomorrow.

&&

.BEACHES...
Issued at 240 AM PDT Tue Jun 10 2025

A long period southerly swell lingers into the day bringing a
higher risk for rip current along beaches. Breaking waves about 5
to 7 feet, but strong currents and sneaker waves will be the
bigger hazard. Use caution near the water and never turn your back
on the ocean.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this
     evening for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt
     Reyes 10-60 NM-SF Bay N of Bay Bridge.

     Small Craft Advisory until 3 AM PDT early this morning for Pt
     Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory until 9 PM PDT this evening for Pt Pinos to
     Pt Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...Murdock
LONG TERM....Murdock
AVIATION...Canepa
MARINE...Sarment

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