Bethel Island, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

075
FXUS66 KMTR 110519
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1019 PM PDT Thu Jul 10 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 1208 PM PDT Thu Jul 10 2025

 - Inland temperatures roughly 10 degrees warmer than yesterday,
   bringing moderate HeatRisk through Friday.

 - Localized elevated fire weather threat continues across higher
   elevations.

 - Gradual cooling trend next week.

&&

.UPDATE...
Issued at 916 PM PDT Thu Jul 10 2025

The marine layer remains compressed around 1000 feet with stratus
filtering in along the coastline. Inland stratus coverage is
expected to be much less widespread tonight than it has been earlier
this week as high pressure continues to build over the region.
Warmer and drier weather continues again tomorrow with highs
expected to be similar to today`s (upper 80s to 90s). A cooling
trend remains on track for this weekend with no major changes to the
overall forecast.

&&

.SHORT TERM...
Issued at 1208 PM PDT Thu Jul 10 2025
(This evening through Friday)

Byron airport in far eastern Contra Costa County crossed into the
90s by noon, but most inland stations are still reporting 70s and
low 80s. Some smoke is propagating into the region, mainly from
the Green Fire in Shasta County. This will filter and reflect some
of the sunlight and should take the edge off the heat today. Our
latest short term forecast keeps the warmest areas generally in
the mid 90s both today and Friday. While these temperatures are
only 5-10 degrees above normal, it may feel worse than that since
we just finished a cool period. Coastal areas will stay in the 60s
and 70s thanks to onshore wind. The marine layer has compressed
to 1,000 feet, which will keep overnight clouds confined closer to
the coast and they should evaporate faster than normal Friday
morning.

&&

.LONG TERM...
Issued at 1208 PM PDT Thu Jul 10 2025
(Friday night through next Wednesday)

There is high confidence that the pattern will remain fairly
stable through early next week with high pressure anchored near
the Channel Islands, embedded in broad high pressure across the
Eastern Pacific. While this high pressure will cause the 850 temp
to build to the 90th percentile for mid-July, we are actually
going to cool off a bit this weekend. The overall pattern supports
onshore wind. With high pressure offshore and to our south, both
downgradient and geostrophic winds are onshore. This synoptic
forcing is enhanced each day as the thermal trough over the
Central Valley deepens. The pressure gradient from SFO to SAC is
expected to fluctuate from +1 mb at night to +4 mb during the day
through early next week. This happens because the ridge brings
afternoon temperatures around 100 degrees in the Central Valley.
This hot air rises and literally lifts a weight off the lower
atmosphere. This induced low pressure then pulls in air from the
Bay Area like a vacuum. With ocean waters in the mid-50s, the
onshore winds act as a natural air conditioning, keeping us much
cooler. By the middle of next week, it looks like a trough will
disrupt the pattern and cool things off across the state. In the
super-long range, there is some indication that a 4-corners high
will start to build around July 22-24, which could bring more
impactful heat late in the month.

&&

.AVIATION...
(06Z TAFS)
Issued at 1019 PM PDT Thu Jul 10 2025

IFR and LIFR CIGS are building along the coast and are affecting HAF
and the Monterey Bay Terminals with mist and drizzle affecting the
immediate coast and slightly inland terminals. IFR CIGs arrive at
APC in the late night and LIFR CIGs and fog affect STS into the
morning. Inconsistent IFR CIGs will move around the SF Bay in the
late night and into Friday morning, affecting SFO and OAK. Fog will
also form around the MRY into Friday morning. Clearing begins in the
mid morning with most TAF sites going VFR in the mid to late
morning. The exception will be HAF, which keeps CIGs through the TAF
period. Winds look to stay light to moderate through much of the
morning, but will increase into the late morning morning and
afternoon. Expect winds to reduce into Friday evening with IFR/LIFR
CIGs returning to the coast along with drizzle and fog.

Vicinity of SFO...Light to moderate winds last through the light.
IFR-level clouds shift through the SF BAY in the late night, and
look to inconsistently fill over SFO and OAK before exiting into
early Friday. Breezy west winds return in the late morning, and look
to last through the mid evening before becoming light again.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...LIFR CIGs and light winds last through the
mid morning with pockets of mist and drizzle affecting visibilities.
Moments of fog also look to affect MRY. Winds become moderate into
mid Friday morning as CIGs erode over the terminals, but expect
cloud cover to linger over the Monterey Bay itself until the mid
afternoon. Winds reduce into Friday evening as IFR/LIFR CIGs
return.&&

.MARINE...
(Tonight through next Wednesday)
Issued at 522 PM PDT Thu Jul 10 2025

Strong northerly breezes over the outer waters will continue
through Saturday with the most hazardous conditions in the far
northwestern portion with gale force gusts and very rough seas.
Sunday and Monday will have a gentle breeze with moderate to
rough seas.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Friday for Pt Arena to Pt
     Reyes 0-10 nm.

     Gale Warning until 9 AM PDT Friday for Pt Arena to Pt Reyes 10-
     60 NM.

     Small Craft Advisory until 9 AM PDT Friday for Pigeon Pt to Pt
     Pinos 10-60 NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Murdock
MARINE...Kennedy

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