FXUS66 KMTR 171141
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
441 AM PDT Mon Aug 17 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1201 AM PDT Mon Aug 17 2026

 - Shallower marine layer through midweek

 - Minor fluctuations in temperatures this week

&&

.SHORT TERM...
Issued at 1201 AM PDT Mon Aug 17 2026
(Today and tonight)

Quiet weather today with little to no impactful weather expected 
through the next week. Temperatures today will be near or slightly 
below normal for this time of year with slightly more mild overnight 
lows to wake up to this morning than we've seen the last few days 
due to mid/high level cloud cover insulating radiative cooling. The 
mid to high level cloud cover will continue out ahead of a 
persistent troughing pattern over the EPAC. The additional cloud 
cover may impact daytime highs as well, limiting peak day heating 
somewhat. Some patchy fog and drizzle may be possible as well, 
especially right along the coastline.

&&

.LONG TERM...
Issued at 1201 AM PDT Mon Aug 17 2026
(Tuesday through Sunday)

Slight shifting in the persistent troughing over the EPAC and the
upper level ridging over the Four Corners region will result in 
subtle warming Tuesday and Wednesday, as the upper ridge pushes 
west slightly. The troughing pushes back to the east for the 
remainder of the week, cooling temperatures a few degrees. 
Overall, temperatures will be on the cooler side of normal for a 
majority of forecast period. There is no clear signal for a 
significant pattern change through the extended forecast.

&&

.AVIATION...
(12Z TAFS)
Issued at 416 AM PDT Mon Aug 17 2026

High clouds and stratus are pushing into the Bay Area and Central
Coast this morning. Stratus coverage is less expansive today than
it has been over the previous two days with the marine layer 
having compressed to approx. 1000 ft. This is bringing IFR 
conditions to interior sites with LIFR conditions along the 
coast. Coastal fog is possible with buoys supporting an upwards 
transport of moisture offshore (a better environment for fog 
development). Conditions improve by late morning with interior 
sites to see VFR conditions this afternoon into the evening. 
Coastal sites are a little trickier as stratus is forecast to hug
the shoreline through the day which may result in patchy stratus
intrusions at coastal sites during the afternoon. Kept HAF 
overcast through the entire day but BKN/OVC ceilings may briefly 
scatter out during the late morning/early afternoon. MRY and SNS 
are more likely to clear out today but cloud cover is expected to 
return during the early evening.

Vicinity of SFO...Stratus is visible on camera approaching SFO but
confidence is low as to the exact timing/duration of the stratus.
The current TAF has a tempo in through 16Z for patchy stratus but
this may need to be extended through 18Z (which ensembles suggest
as a reasonable late clearing time for today). Given that the
marine layer will be compressed again tonight, I pushed back the
timing for stratus return tonight to closer to 10Z. Confidence is
low to moderate on timing given that stratus is expected to be
patchy again tonight.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR-LIFR ceilings continue through late
morning before a brief period of VFR conditions returns this
afternoon. This is short lived with IFR-LIFR conditions returning
shortly after 00Z. Reductions in visibility become more likely
towards the end of the TAF period with a low potential for fog to
develop at both sites. Breezy onshore winds return during the
afternoon and evening before winds decrease overnight.

&&

.MARINE...
(Today through Saturday)
Issued at 416 AM PDT Mon Aug 17 2026

Winds gradually increase today with a fresh to strong breeze
developing by late tonight and continuing through the end of the
forecast period. Locally stronger winds are possible in the
coastal jet regions north of Point Reyes and along the Big Sur
coast. Seas build to 7 to 9 feet by Tuesday and Wednesday before
abating late week. A long period southerly swell around 14 to 15
seconds will continue to subside through the early work week.

&&

.FIRE WEATHER...
Issued at 1205 AM PDT Mon Aug 17 2026

Nocturnal drying through at least mid-week as the marine layer 
gradually compresses. Expect more widespread fair to moderate 
recoveries developing over the higher elevations, especially in 
and around the Timber Fire.

&&

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

&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...Kennedy
MARINE...Kennedy

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Prepared by Boulder-Creek.com Weather at: Mon Aug 17 06:30:02 PDT 2026