440
FXUS66 KMTR 172310
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
410 PM PDT Thu Jul 17 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 155 PM PDT Thu Jul 17 2025

 - Slight warming trend to seasonal temperatures Friday through
   the weekend before below normal temperatures return Monday.

 - Localized elevated fire weather threat continues across the
   higher elevations with drier conditions beginning this weekend.

 - Winds strengthen early next week.

&&

.SHORT TERM...
Issued at 155 PM PDT Thu Jul 17 2025
(This evening through Friday)

The marine layer will start to compress tonight as troughing over
the West Coast is pushed northward over OR/WA by weak high pressure
building in over California. Guidance shows high pressure building
more slowly throughout the day with Friday acting as more of a
transition day from weak/subtle troughing to weak high pressure. The
main change to the forecast is how much temperatures will warm.
Temperatures across the board will warm between 1 to 5 degrees on
Friday. For the lower elevations, this pushes most sites closer to
seasonal averages, but, most will remain at least slightly cooler
than normal. Across the higher elevations, temperatures have been
closer to seasonal averages so this slight warm up will push
temperatures to seasonal to slightly above normal. What specifically
does that mean for tomorrows high temperatures? Areas closer to the
SF Bay Shoreline will only warm 2-3 degrees with highs in the mid to
upper 70s while areas away from the bay shoreline will be in the
upper 70s to 80s. Residents of interior Monterey and San Benito
counties may feel this warm up more than residents of the Bay Area
with highs rising from the low to mid/upper 90s. Coastal residents
continue to benefit from the natural A/C of the marine layer with
temperatures staying in the upper 50s to 60s.

In terms of stratus and drizzle chances, the marine layer was around
2000 ft as of the 12Z OAK sounding this morning. With high pressure
building in more slowly tomorrow, another night of widespread
stratus is expected across the Bay Area and Central Coast. There is
some potential for coastal drizzle tonight, but, this is mainly
limited to the coastal North Bay with chances decreasing along the
rest of the coastline.

&&

.LONG TERM...
Issued at 155 PM PDT Thu Jul 17 2025
(Friday night through next Wednesday)

Temperatures will be fairly similar on Saturday to those observed on
Friday, upper 70s along the Bay Shoreline, upper 70s to 80s farther
away from the shoreline, and 90s across the far interior East Bay
and Central Coast regions. This will keep us with seasonal to
slightly below normal temperatures across the majority of the Bay
Area with only the higher elevations seeing slightly above normal
temperatures. Temperatures will peak on Saturday for the interior
Central Coast but peak on Sunday for the Bay Area as high pressure
becomes more dominant across the region. This will bring
temperatures largely into the 80s across the interior and low to mid
90s across the interior East Bay and Central Coast. Temperatures
cool down well overnight (50s to 60s) with only Minor HeatRisk
forecast across interior regions through the weekend.

Thought you`d seen the last of No Sky July? Nope. Upper level
troughing is forecast to return across our area early next week and
continue through the end of the forecast period. This will see
temperatures dropping below normal again with high temperatures
falling back into the mid 70s to low 80s across the interior.
Temperatures across the interior Central Coast will continue to be
seasonal to slightly above normal in the upper 80s to low 90s. The
marine layer looks to deepen again Monday with widespread overcast
conditions likely to return again each night starting Monday. CPC
guidance indicates temperatures are likely to remain below normal
through the end of July as upper level troughing continues.Gusty
onshore winds return to mountain gaps/passes, valleys, and along
the coast late Sunday through Monday as the upper level trough
approaches. EFI guidance highlights the potential for stronger
winds in the vicinity of the East Bay Hills and eastern Napa
County with the strongest winds expected over the Sacramento
Valley.

Localized elevated fire weather concerns continue across the higher
elevations and interior Central Coast. Seasonal to slightly above
normal temperatures continue across these regions with daytime
humidity values dropping as low as 15% Saturday and Sunday. Winds
generally remain light and onshore, but, diurnally breezy winds
gusting to around 30 mph are expected to develop each
afternoon/evening in the Salinas Valley. Dry conditions will persist
through the end of the forecast period with daytime minimum humidity
values in the 20%-30% range as upper level troughing returns.

&&

.AVIATION...
(00Z TAFS)
Issued at 409 PM PDT Thu Jul 17 2025

Generally MVFR stratus persists along patches at the immediate
coast, with a finger of clouds streaming through the Golden Gate
dissipating before it reaches the East Bay. Generally VFR conditions
inland continue through the evening hours, with breezy onshore winds
continuing through that period. Winds will diminish later this
evening as stratus builds inland overnight into early Friday
morning. Stratus retreats to the immediate coast Friday morning with
breezy onshore flow resuming in the afternoon.

Vicinity of SFO... VFR through the evening with MVFR-IFR stratus
developing overnight. Breezy westerly flow will diminish in the
evening hours, becoming light overnight before resuming Friday
afternoon. Stratus will return sometime Friday evening, although
there is moderate confidence on timing of impacts, they should
develop before the end of the TAF period.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR for the next few hours, with stratus
returning as early as 02-03Z. Monitoring the potential for the
stratus feed through the Bay impacting SNS before the current
forecast of 03Z. Stratus should retreat to the immediate coast
Friday morning with some model indications of a rather early return
of stratus to MRY on Friday evening. Breezy onshore winds diminish
through the evening, becoming light overnight before resuming Friday
afternoon.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 409 PM PDT Thu Jul 17 2025

Expect a light to moderate westerly or northwesterly breeze
across the majority of the coastal waters through this weekend.
Gusty winds, potentially hazardous to small craft, develop each
afternoon and evening through the Golden Gate and into the Delta
as well as the favored coastal jet along the Big Sur coastline.
Moderate seas also continue through the remainder of the forecast
period.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM Friday to 3 AM PDT Saturday for
     Pt Pinos to Pt Piedras Blancas 0-10 nm-SF Bay N of Bay
     Bridge.

&&

$$

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

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