Hercules, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

700
FXUS66 KMTR 091130
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
430 AM PDT Wed Jul 9 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 101 AM PDT Wed Jul 9 2025

 - Warming trend begins today through the weekend, with patchy
   Moderate HeatRisk across the Bay Area and Central Coast
   Thursday and Friday.

 - Localized elevated fire weather threat starting today through
   the weekend across the higher elevations.

&&

.SHORT TERM...
Issued at 101 AM PDT Wed Jul 9 2025
(Today and tonight)

Satellite imagery shows widespread marine layer stratus across the
valleys of the Bay Area and Central Coast, as data from the Fort Ord
profiler shows the top of the marine layer becoming more diffuse
while rising to at least 3000 feet over the last evening. Low
temperatures this morning will hover in the lower to middle 50s in
the lower elevations, and as high as the lower 60s in the highest
peaks.

Today marks a pattern change from the cooler regime of the last few
days to a warming pattern that (spoiler alert) looks to set up for
the rest of the week. The upper level low that brought us the robust
marine layer and the cool temperatures is dissipating while it
meanders towards landfall in the North Coast. This will allow an
ridge that`s set up over the desert Southwest to edge into the state
while a synoptic high pressure system develops in the east Pacific,
causing temperatures to warm. Temperatures will range from the upper
70s to the middle 80s inland, with the warmest spots in southern
Monterey and San Benito Counties reaching the upper 90s, while
locations on the Bays reach highs in the upper 60s and the 70s. The
marine layer will compress, but the coastal areas should remain
rather cool with highs in the upper 50s to the lower 60s.

Some elevated fire weather threat is forecast to develop today
across areas above and inland of the marine layer`s influence. The
combination of dry daytime humidities of around 15-30% and localized
gusts to 30 mp will be the main factors behind the elevated threat.
However, the winds will remain onshore, leading to the fire weather
threat being diurnally driven, especially in the foothills where
lighter winds and good overnight recoveries are expected each
night.

&&

.LONG TERM...
Issued at 101 AM PDT Wed Jul 9 2025
(Thursday through Tuesday)

Temperatures continue to rise on Thursday and Friday as the high
pressure systems become more established, with the inland valleys
seeing highs in the middle 80s to middle 90s on both days, while the
warmest interior locations see temperatures rising up to a few
degrees above 100. Patches of Moderate HeatRisk are expected on
Thursday and Friday across the interior North Bay, East Bay, and
South Bay, in addition to the Santa Lucia mountains and the southern
tip of San Benito County. Remember to take frequent cooling breaks
and drink plenty of water if participating in outdoor activities on
both days.

As a very weak upper level disturbance passes through the state this
weekend, temperatures will cool slightly to the lower 80s to lower
90s in the interior Bay Area with an shortwave trough coming through
the West Coast, while the interior Central Coast remains rather warm
with temperatures in the 90s. The pattern will otherwise remain
rather stable through the early part of next week, with warm inland
temperatures, cool coastal temperatures, light onshore winds, and
localized elevated fire weather threat in the interior developing
each afternoon.

&&

.AVIATION...
(12Z TAFS)
Issued at 419 AM PDT Wed Jul 9 2025

MVFR to LIFR ceilings early this morning with a robust marine
layer in place. Conditions will persist through most of the
morning into the early afternoon for some spots. Expect some
breezy periods of onshore flow this afternoon with a return of low
stratus ceilings around sunset for most, after midnight for the
North Bay locations.

Vicinity of SFO...MVFR/IFR stratus ceilings will persist through
the late morning, clear out for much of the afternoon and early
evening, then returning around sunset with a 2500` marine layer in
place.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR/LIFR persisting through most of the
morning with clearing expected around noon. HiRes guidance is
anticipating a later clearing this morning than yesterday and
earlier return this evening with the marine layer topping out at
2500`. Onshore flow may breezy at times this afternoon.

&&

.MARINE...
(Today through Monday)
Issued at 419 AM PDT Wed Jul 9 2025

Winds will begin to increase out of the north this afternoon and
continue to strengthen through Wednesday night becoming fresh to
strong for Thursday into the weekend. Rough to very rough
significant wave heights will also persist into the weekend for
the outer waters.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT
     Thursday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Small Craft Advisory from 3 PM this afternoon to 3 PM PDT
     Thursday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...JM
MARINE...JM

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