FXUS66 KMTR 102154
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
254 PM PDT Mon Aug 10 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 144 PM PDT Mon Aug 10 2026
- Elevated fire weather conditions in the higher terrain Monday
- Minor coastal flooding for bayshore locations along the San Francisco
Bay, San Pablo Bay, and Monterey Bay through Thursday morning
- Cooling trend through Thursday will bring well below normal
temperatures
- Up to a 15% chance for elevated rain showers/thunderstorms
Wednesday with high confidence over the Central Coast
&&
.SHORT TERM...
Issued at 144 PM PDT Mon Aug 10 2026
(This evening through Tuesday night)
Afternoon visible satellite imagery shows ample sunshine across
the interior, but the persistent marine layer continues to hug
the coast. Pretty interesting to see all of the small eddies
forming in the coastal stratus this afternoon as well. Satellite
imagery also shows heat and smoke associated with the Timber
Incident along the Big Sur coast. Monterey Airport was reporting
haze at various times through the day due to some drift smoke.
Overall transport flow is not overly strong through Tuesday so
smoke/haze will be possible around the Monterey Bay / Big Sur
region.
Interesting longwave pattern across CA tonight through Tuesday.
The large ridge that brought oppressive heat to CA over the
weekend has been split in half by a deepening upper level trough.
One upper ridge is near the Four Corners and the other is well
offshore. Sandwiched in the middle is a small shortwave trough
inching its way toward the CA coast. Over the next 24 hours the
trough will deepen further cooling the airmass and deepening the
marine layer. The cooling trend noticed across the forecast area
today will continue on Tuesday. Additionally, as the trough
deepens a few spokes of moisture and instability will traverse the
Central Coast. For now, not enough to warrant any mention of
precip, but a few high level Cu are possible. Speaking of precip,
the moisture in the marine layer will be high enough for coastal
drizzle.
&&
.LONG TERM...
Issued at 240 PM PDT Mon Aug 10 2026
(Wednesday through next Sunday)
For Wednesday an upstream feature gets enhanced by a jet max west
of Pt Conception. This feature has peaked our interest as it will
lead to a low confidence high impact scenario. Latest model
guidance shows there is enough moisture and instability to at
least warrant a mention of showers and thunderstorms. Pt forecast
soundings shows decent instability, dry low levels, but some CIN
leading to the lower confidence. Pattern recognition also brings
some pause as previous fires in 1999 and 2008 had upper level
disturbances off the Central Coastal. This setup is close, but
not exactly like previous lightning busts. As such, decided to not
issue any Fire Weather Headline, but add 15% chc of
showers/thunderstorms to Monterey/San Benito Wednesday afternoon
and evening. Outside of the convective threat, sensible weather
trends continues. Cooler weather for Wednesday and Thursday. Night
and morning clouds clearing to the coast each afternoon. Coastal
drizzle has been added to the forecast.
Over the weekend a subtle warming trend develops as a low deepens
near the Gulf of AK and drops south. The southward trajectory well
offshore of the West Coast will also the inland Four Corners
ridge to ease westward.
&&
.AVIATION...
(18Z TAFS)
Issued at 1033 AM PDT Mon Aug 10 2026
Lingering IFR-LIFR stratus is dissipating across the North Bay
valleys, the San Francisco Bay, and the northern Salinas Valley, and
the mixing out is expected to continue through the morning as the
stratus deck pares back to the immediate coastal region. Moderate
onshore pattern winds will develop during the afternoon and evening
hours with gusts of 15 to 25 kt. Stratus will return inland during
the evening and overnight hours. Moderate confidence in the high
resolution model output that keeps most of the SF Bay clear through
the night.
Vicinity of SFO... VFR through the evening hours. Light offshore
flow will turn to the west-northwest with gusts of 25 kt during the
afternoon and evening hours. High resolution model output keeps the
terminal area clear through the night as southwest winds develop
aloft, there is moderate confidence in the forecast at this time.
Tuesday afternoon, expect breezy and gusty winds to resume with a
southwest component, leading to lower confidence on wind direction
this far out.
SFO Bridge Approach... Similar to SFO.
Monterey Bay Terminals... VFR at SNS through the daytime, MRY will
clear out within the next couple of hours. Gentle onshore winds will
develop in the afternoon and evening. IFR-LIFR stratus returns
rather early in the evening, with some high resolution model output
seeing stratus returning to MRY as early as 01-02Z. Clearing is
expected to be delayed to near or slightly after the end of the TAF
period.
&&
.MARINE...
(Today through Saturday)
Issued at 1033 AM PDT Mon Aug 10 2026
Fresh to strong northwest winds persist through Thursday with
rough seas up to 12 feet over the northern outer waters and
occasionally the inner waters north of Point Reyes. The San Pablo,
Suisun Bays and the Delta will continue to see gusty onshore
winds through the early evening hours. Long period southerly
swells around 15 seconds will continue through much of the work
week.
&&
.FIRE WEATHER...
Issued at 205 PM PDT Mon Aug 10 2026
Timber Fire - complicated weather around the vicinity of the
Timber Fire. There will be a vast difference is weather along Hwy
1 and along Coast Ridge Rd. The marine layer will keep the Hwy 1
region cool, damp, and drizzly. Above the marine layer will
remain mild and dry. Above the marine layer is also a region that
has baked and dried over the last 7 to 10 days with little to no
relief. Thankfully, wind does not appear to be overly strong.
Very diurnally driven wind patterns.
The real wild card for the Timber Fire will be thunderstorm
chances on Wednesday. REad the long term above for more details.
After coordinating with neighboring offices and fire partners
decided to mention the chance and not issue any Red Flag at this
time.
MM
From the previous discussion, which is still valid for today. May
obs as of 230PM show RH less than 20% and winds gusts 10-20 mph.
Elevated fire weather conditions persist Monday across the higher
terrain due to an increase in onshore flow on the heels of very hot
and dry conditions. Slow improvement is expected with temperatures
still 10 degrees above normal and minimum relative humidity of 15%-
30% Monday afternoon. Gusts up to 30 mph can be expected through
gaps/passes and across ridgelines; namely, the Delta, Altamont Pass,
Pacheco Pass, and Interior Mountains of Monterey and San Benito
Counties. Moderate overnight recovery is expected Monday night;
however, the highest terrain of the Central Coast will likely remain
poor.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 2 AM PDT Thursday for CAZ006-506-
508-529-530.
PZ...Small Craft Advisory until 9 PM PDT this evening for SF Bay N of
Bay Bridge.
Small Craft Advisory until 9 PM PDT Wednesday for Pt Arena to Pt
Reyes 10-60 NM.
&&
$$
SHORT TERM...MM
LONG TERM....MM
AVIATION...DialH
MARINE...DialH
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
Prepared by Boulder-Creek.com Weather at: Mon Aug 10 16:30:02 PDT 2026
From the National Weather Service
|