FXUS66 KMTR 251944
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1244 PM PDT Tue Aug 25 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1242 PM PDT Tue Aug 25 2026
- A shallow marine layer will keep coastal conditions near
normal through Thursday
- Seasonably warm and very dry conditions continue above 1000
feet and across the far interior through Thursday
- Pattern change Friday into the weekend brings cooler
temperatures and moderate potential for tropical moisture
&&
.SHORT TERM...
Issued at 1242 PM PDT Tue Aug 25 2026
(This evening through Wednesday night)
Regional satellite imagery is showing stratus retreating to the
immediate Pacific coastline with abundant sunshine expected across
the interior this afternoon. Meanwhile, passing high clouds also
persist and are moving northeastward across region. Thus, interior
temperatures will warm into the 80s to mid 90s and up to around
105 deg F in the warmest interior parts of Monterey County.
Persistent onshore and a shallow marine layer will keep
temperatures near seasonal averages near the coast. Breezy onshore
winds are forecast to develop by this afternoon and evening, with
gusts up to 20 to 35 mph along the coast and in the favored
valleys and passes.
Tonight, expecting stratus to return inland late this evening and
into the interior valleys by Wednesday morning. However, the
inland extent may be less than previous days as the marine layer
compresses slightly.
For Wednesday, a slight up tick in temperatures as the ridge
builds further west across the Desert Southwest. As such,
temperatures will be some 5-10 degrees F above average with 10-20
degrees F above average in the far interior and higher elevations
above 1000 feet. We are still expecting warm and very dry
conditions above the marine influences with little to no overnight
humidity recoveries through Thursday. See the FIRE WEATHER
section for the implications for local fire weather concerns. &&
.LONG TERM...
Issued at 1242 PM PDT Tue Aug 25 2026
(Thursday through next Monday)
Afternoon temperatures will be slightly cooler on Thursday as a
trough of low pressure approaches the West Coast, however 850 MB
temperatures will remain between 23-26 degree C. The cooling trend
will become more noticeable Friday and moreso into the upcoming
weekend and early next week as the trough deepens over the Pacific
Northwest. Thursday night into Friday, we are expecting mid/upper
level tropical moisture to advect northward across the Bay Area
and Central Coast. This will definitely increase high cloud cover
and also result in an increased potential for high-based rain
showers and/or thunderstorms. However, the lack of instability
looks to be the limiting factor for thunderstorms. We are
monitoring this closely at this time.
Expecting breezier conditions with the deepening trough off of
the West Coast. Gusts are forecast to be between 25 to 35 mph
near the coast and in the favored valleys, gaps, and passes by
Friday and into the weekend. By Monday, temperatures are forecast
to be some 5-15 degrees F below seasonal averages which matches
with the CPC's 6-10 Day Temperature Outlook.
&&
.AVIATION...
(18Z TAFS)
Issued at 1206 PM PDT Tue Aug 25 2026
Stratus quickly dissipated out of the remaining terminals and
widespread VFR prevails this afternoon. Onshore winds should remain
moderate throughout the day and ease to gentle overnight. Rather
tricky stratus forecast this TAF period. Model guidance is trying to
indicate a widespread compressed marine layer tonight into tomorrow,
but it is not convincing when compared to observations. Per the OAK
sounding this morning, the marine layer was measured at a depth of
around 1700 feet. Closer to Monterey Bay, the marine layer is around
1200 feet. That being said, highest confidence for IFR to LIFR
ceilings at HAF, MRY, and SNS around sunset. Low confidence on
whether SJC will develop a ceiling as it depends on how deep the
marine layer decides to be tonight. The other Bay Area terminals can
expect IFR to low-end MVFR ceilings to arrive around or after sunset.
Vicinity of SFO...VFR with northwest breezes increasing to fresh
through the afternoon and diminishing to gentle overnight. If the
stratus pattern from this morning holds, IFR ceilings may develop
shortly after sunset and dissipate by late Wednesday morning. The
current TAF relies a bit on persistence from last night, but overall
low to medium confidence on the exact timing.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR through the day as northwest winds
remain around 10-12 kt. Stratus is expected to bring IFR ceilings
around 7-8 PM PDT this evening as winds become light. Ceilings may
drop to LIFR overnight which will reduce visibility due to either
mist or fog. Stratus should clear by late Wednesday morning.
&&
.MARINE...
(Tonight through next Sunday)
Issued at 1206 PM PDT Tue Aug 25 2026
Moderate northwest breezes become fresh to strong Wednesday and
persists through the week. Wind driven seas remain moderate into
the weekend. A long period southerly swell around 15 to 17
seconds continues to build by the end of the week.
&&
.FIRE WEATHER...
Issued at 1202 AM PDT Tue Aug 25 2026
Near-critical fire weather conditions continue through Thursday for
elevations above 1000 feet as warm and dry conditions continue
across the region. Humidity recoveries remain poor to very poor in
the higher elevations, with nocturnal drying expected within the
Santa Lucia range. Breezy conditions will develop each afternoon and
evening, but not for a long enough period to trigger any fire
weather products. Specifically regarding the Timber Fire vicinity,
observational data suggests that southwesterly winds from the
Pacific Ocean over the ridgetops are helping to moisten the air,
with nocturnal drying being observed as the winds diminish and even
turn faintly offshore overnight. This has led to an unusual
situation where daily maximum relative humidity values have been
observed during the daytime. Smoke transport from the Timber Fire
will continue to peak in the afternoon and evening with the plume
spreading towards the Salinas area. Friday into the weekend, a
pattern change should allow for some relief as an upper level trough
comes into the region bringing cooler temperatures and a deeper
marine layer.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT Thursday for Pigeon Pt to Pt
Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt
Piedras Blancas 0-10 nm.
Small Craft Advisory from 9 PM this evening to 9 AM PDT Thursday
for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-
60 NM.
&&
$$
SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Navarrete
MARINE...Navarrete
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Prepared by Boulder-Creek.com Weather at: Tue Aug 25 16:30:03 PDT 2026
From the National Weather Service
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