457
FXUS66 KMTR 131951
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1251 PM PDT Sun Jul 13 2025

...New SHORT TERM...

.KEY MESSAGES...
Updated at 1250 PM PDT Sun Jul 13 2025

 - Temperatures near to slightly below seasonal averages with a
   more noticeable cooling trend beginning Tuesday.

 - Localized elevated fire weather threat continues across the
   higher elevations.

&&

.SHORT TERM...
Issued at 1250 PM PDT Sun Jul 13 2025
(This evening through Monday)

Temperatures this afternoon will be similar to those yesterday.
Generally expecting the coastal areas to be in the upper 50s to
lower 70s where low stratus looks most likely to prevail. The
interior will warm into the upper 70s to lower 90s and the far
inland areas of the North Bay, East Bay, South Bay and interior
Monterey/San Benitio County reaching or exceeding 100 degrees F (but
only in isolated spots).

Stratus will return back inland into the coastal valleys tonight and
into early Monday morning. There is also the potential for coastal
drizzle again tonight and has been added to the official forecast.
Low clouds retreat back to the coast by mid/late Monday morning
resulting in sunny skies across the inland areas. Meanwhile, coastal
locations may very well remain under cloudy or mostly cloudy skies.

Monday afternoon will feature similar temperatures as today!

From previous forecaster: "Localized elevated fire weather threat
persists across areas above and inland of the marine layer`s
influence. The combination of dry daytime humidities of around 20-
35%, poor overnight recoveries of 25-40%, and localized gusts to 25
mph 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 1229 AM PDT Sun Jul 13 2025
(Monday night through Saturday)

Late on Monday, a shortwave trough, or perhaps a weak cutoff low,
develops into the Pacific Northwest, pushing the ridge axis
towards the west and north and causing a noticeable cooling trend
to begin on Tuesday and lasting for at least the following two
days. High temperatures drop into the middle 70s to middle 80s
inland and the upper 60s to the middle 70s along the Bayshore,
with the coast remaining rather stable at the upper 50s to lower
60s.

Towards the end of the forecast period, the forecast becomes a
little more uncertain. Ensemble model cluster analysis points to
weak ridging (i.e. warmer temperatures) and weak troughing (i.e.
cooler temperatures) by Friday, with the differences compounding
through the upcoming weekend into the early part of the following
week, when a significant ridge and a significant trough are possible
across the western United States. With the two scenarios having
nearly equal probabilities, there is not enough confidence at this
time to deviate from the default NBM forecast, which depicts a
gradual warming trend heading into the upcoming weekend. CPC
outlooks suggest a slight lean towards temperatures above seasonal
averages in the 8-14 day period (July 20-26).

&&

.AVIATION...
(18Z TAFS)
Issued at 951 AM PDT Sun Jul 13 2025

Currently a mixed bag of LIFR-VFR at the terminals with VFR
expected shortly at all terminals with the exception of HAF which
is slated to remain sub-VFR through the TAF period. High
confidence in all terminals deteriorating to sub-VFR conditions
again tonight as the pattern largely remains unchanged. Coastal
drizzle will be possible during the overnight and morning hours.
Smoke from wildfires burning in Northern California will likely
filter into the region and reduce slight range visibilities.

Vicinity of SFO...Currently VFR with northwesterly flow. Westerly
flow will return once the sea breeze kicks in this afternoon. High
confidence in sub-VFR ceilings returning tonight, likely on the cusp
of IFR/MVFR.

SFO Bridge Approach...The approach still has some low stratus this
morning, but that should evaporate very quickly. Low stratus clouds
will begin to filter in through the Golden Gate Gap by 01Z with
visuals likely being impacted through 18Z Monday.

Monterey Bay Terminals...Currently LIFR with westerly flow at MRY
and IFR and calm at SNS. Both terminals are expected to improve to
VFR shortly with stratus sticking to the coast during the day. High
confidence in LIFR ceilings returning to both terminals tonight.

&&

.MARINE...
(Today through Friday)
Issued at 824 AM PDT Sun Jul 13 2025

Localized hazardous marine conditions in the form of strong
northerly breezes and very rough seas will be present Monday and
Tuesday for the northern outer waters. Aside from that, a gentle
to moderate breeze with moderate to rough seas will prevail
through Thursday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM Monday to 3 AM PDT Tuesday for Pt
     Arena to Pt Reyes 10-60 NM.

&&

$$

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

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