Discovery Bay, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

778
FXUS66 KMTR 052102
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
102 PM PST Fri Dec 5 2025

...New SHORT TERM...

.KEY MESSAGES...
Updated at 1215 PM PST Fri Dec 5 2025

 - Persistent forecast through the next seven days with benign
   conditions and no precipitation expected

 - Impacts from Tule Fog in the North Bay and interior East Bay
   valleys

 - Next chance for rain towards the middle of the month

&&

.SHORT TERM...
Issued at 1259 PM PST Fri Dec 5 2025
(This evening through Saturday)

Owing to the slower than expected stratus mix out and warming in
the valleys of the North Bay and interior East Bay, have opted to
decrease today`s highs and tonight`s lows in both areas, with the
high temperatures now expected to rest in the middle to upper 50s
and lows in the upper 30s to lower 40s in the area, with areas in
the eastern tier of Contra Costa County going up to the lower 50s
today.

For all other regions, the previous discussion is still valid: Satellite
imagery reveals lingering impacts from the Tule Fog spillover
across the valleys of the North Bay and the interior East Bay. The
mix out process continues to be rather slow with marginal
shrinkage of the stratus deck in the late morning, with the bulk
of the mixing out expected to occur this afternoon into the
evening. There is also a potential for drizzle to develop in the
coastal waters tonight, fringe effects of a storm system that is
bringing rain to the Pacific Northwest but is not expected to
bring any precipitation on the land side of the Bay Area and
Central Coast. This, in turn, could support the return of coastal
stratus to the region. Otherwise, the weather remains generally
clear through the day, as upper level ridging dominates the
western United States. High temperatures today and Saturday range
from the lower to middle 60s across the inland valleys, with the
southern Salinas Valley reaching the upper 60s to near 70, and the
upper 50s and the lower 60s near the coast. Lows will generally
range from the lower to middle 40s inland and the middle to upper
40s along the coast. Some locations in southern Monterey County
will drop into the middle 30s. Will need to monitor the need for a
Cold Weather Advisory if the temperatures drop due to enhanced
radiational cooling, or if temperatures in the North and East Bays
stay cool due to lingering stratus impacts reducing the daytime
heating effects.

&&

.LONG TERM...
Issued at 1215 PM PST Fri Dec 5 2025
(Saturday night through next Thursday)

Ridging will dominate the weather patterns through the rest of the 7-
day outlook, enabling a gradual warming trend across the region.
Rather than a day when the temperatures shoot upwards, we will
experience a extended crescendo where the highs shoot up by a degree
or two each day until you notice that by the middle of next week,
temperatures are running 5 to 10 degrees above seasonal averages and
highs in the inland valleys have reached the upper 60s to middle
70s. By the end of the 7-day forecast period, there are hints that a
burst of offshore flow could come to the region, although exactly
how strong that flow will be is open to lots of refinement.

Longer range model guidance suggests a possible change in the
weather pattern towards the middle of the month. Ensemble model
cluster analysis depicts the majority of model runs showing a
continuing ridge, but substantial minorities (somewhere around 30-
40% of the ensemble members) depict a breakdown of the ridge. CPC
guidance continues to show a slight lean, emphasize, a slight lean,
towards precipitation totals above seasonal averages for December 13-
19 across the Bay Area. For context, within the long-term climatic
averages, downtown San Francisco receives a little over an inch of
rain during this period.

&&

.AVIATION...
(18Z TAFS)
Issued at 938 AM PST Fri Dec 5 2025

Patchy to areas of fog persist across the North Bay and East Bay
valleys this morning and are forecast to improve between 19- 20Z.
This will give way to mostly VFR conditions after low ceilings and
visibilities improve. Onshore winds look to increase by this
afternoon across the San Francisco Bay and Monterey Bay terminals
before easing late this evening and into Saturday morning. This is
when low ceilings and/or visibilities are expected again in the
North Bay and East Bay valleys early Saturday morning. Any low
ceilings and/or visibilities that do develop are expected to clear
at a similar time as today.

Vicinity of SFO...VFR through the TAF period. Offshore winds
prevail this morning and are expected to become north-
northwesterly by mid- to-late afternoon. Winds diminish overnight
with moderate to high confidence of onshore winds returning by
Saturday afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period. Light to
southerly winds prevail this morning and are forecast to become
onshore by early-to-mid afternoon. Winds diminish overnight and
become southerly early Saturday morning.

&&

.MARINE...
(Today through Wednesday)
Issued at 828 AM PST Fri Dec 5 2025

Northerly winds are increasing across the waters with fresh to
strong gusts expected. Localized near gale force gusts are
possible across the outer waters and in the favored coastal jet
regions through the weekend. These winds persist into the upcoming
work week. Moderate seas continue with seas building to between 6
to 8 feet Friday through Sunday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 3 PM PST Sunday for CAZ006-506-508-
     529-530.

PZ...Small Craft Advisory until 3 AM PST Saturday for Pt Arena to Pt
     Reyes 0-10 nm.

     Small Craft Advisory from 9 AM Saturday to 3 AM PST Sunday for
     Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 9 AM PST Saturday for Pt Arena to Pt
     Reyes 10-60 NM.

     Small Craft Advisory until 3 AM PST Sunday for Pigeon Pt to Pt
     Pinos 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...RGass
MARINE...RGass

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, X, and YouTube at:
www.facebook.com/nwsbayarea
x.com/nwsbayarea
www.youtube.com/nwsbayarea