FXUS66 KMTR 132348
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
348 PM PST Tue Jan 13 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 200 PM PST Tue Jan 13 2026

 - Chilly mornings, but very mild afternoons over the next 5 to 7
   days

 - Morning fog across the delta and East Bay

 - Elevated risk for sneaker waves and rip currents at Pacific
   coast beaches

&&

.SHORT TERM...
Issued at 200 PM PST Tue Jan 13 2026 
(This evening through Wednesday)

Tranquil conditions are anticipated to continue through the short
term forecast period. Water vapor imagery at this hour shows our
H5 ridge remains parked across our region. In addition to a few 
upper level high clouds, large scale subsidence should result in 
fair weather over the next 5 to 7 days. The MinT forecast remains 
a little tricky as the column remains dry and skies are mostly
clear. This would typically promote very ideal radiational
cooling. In fact, our 12Z RAOB PWAT of 0.25" is actually closer 
to the 10th percentile for this time of year. This dry airmass has
allowed temperatures to climb quickly into the 60s, with the 
warmer spots across the Central Coast. As noted in the update this
morning, we'll see a rather sharp diurnal temperature curve and I
anticipate that we'll still have some chill in the air by 
daybreak Wednesday. The discernible difference between Wednesday 
morning and the previous AM's will be an uptick in the 925mb flow.
Forecast speeds are anticipated to range between 5 and almost 15 
knots in some spots. While seemingly meager, this may perturb the 
PBL sufficiently such that it doesn't fully decouple and optimize 
radiational cooling. The probability of locales dipping down to or
below 32F appears to be less than 10% across the area, though 
some of the sheltered/valley locations may still have an 
opportunity to see temperatures fall down to near "freezing" as 
these locales may more readily decouple from the free atmosphere.
All that to say, widespread cold similar to the previous nights is
NOT expected on Wednesday morning. That said, continue to protect
any sensitive plants/vegetation if compelled and always use 
appropriate indoor heating appliances.

The other impact of the wind may be to limit the widespread fog
development. Similar to the cold, areas that are more sheltered
from the wind (lower elevations) and areas near bodies of water
may have a higher fog potential. Currently, the best 
probabilities for fog, occasionally dense, will be across the 
North Bay river valleys, and across portions of the East Bay 
(where Tule Fog may attempt to encroach across the area). 

Wednesday should be another pleasant day with highs in the 60s to
mid 70s. In fact, there are some hints of 80 degree weather
(around a 15-20% chance) across the Santa Lucias, the Diablo 
Range, and Santa Cruz Mountains on Wednesday. Quite pleasant for 
the typical "rainy" season and certainly above normal (by 10 to 15
degrees) for this time of year. "Minor" HeatRisk is advertised 
and this equates to some heat impacts for very sensitive groups. 
However, the primary hazard may be the elevated risk for rip 
currents and sneaker waves, so be mindful of this threat if you're
heading to the water.

&&

.LONG TERM...
Issued at 200 PM PST Tue Jan 13 2026 
(Wednesday night through next Monday)

The pleasant conditions are forecast to continue into this weekend
as mid/upper level ridging remains in place across our area.
Morning fog/stratus should dissipate quickly with daytime heating
and turbulent mixing. We'll keep tabs on the westward extent of
any Tule fog that develops across the Central Valley, but at this
time, impacts are expected to be confined to interior reaches of
the North Bay and East Bay. The warmest day in the outlook period
appears to be Thursday at this time. However, depending on how 
the airmass modifies and the exact position of the mid-level 
ridge, the warming trend could continue this weekend.

High pressure will really dominate the weather through the long
term period, with guidance indicating it'll remain anchored across
our region. There's high confidence in the synoptic pattern as the
multi-model ensemble exhibits very little in the way of spread 
through at least this weekend. As we have been advertising 
through the week, the nice weather will make for very ideal beach 
conditions. With a continued risk for longer period westerly 
swell, the threat for sneaker waves and rip currents will persist.
Be sure to check conditions before you head to the beach.

While the multi-model ensemble largely mimics a majority of the
clustered NWP solutions, there is some variability in the extent 
of the upper ridge as we get toward the end of the weekend. Toward
the middle of next week, some guidance advertises a potent upper 
trough will dive through Big Sky Country and this may start to
dislodge our ridge westward. This would potentially crack the 
storm door open as upper troughing amplifies. Nothing appears 
overly impactful at this time, but we are trending toward 
temperatures returning to near or even falling below normal with 
perhaps the region's next opportunity for measurable rainfall by
the middle to end of next week.

&&

.AVIATION...
(00Z TAFS)
Issued at 344 PM PST Tue Jan 13 2026

VFR this afternoon with the exception of some HZ at KHAF causing
reduced VIS. Confidence is high that KSTS will see another foggy 
night; however, confidence is moderate to low on who else might 
see reduced VIS due to fog. A decent amount of MOS guidance and 
hi- res models indicate visibilities falling to MVFR categories 
from roughly 9Z-18Z, with visibility improving around or shortly 
after 18Z. Opted to hint at that with the possibility of 
VIS going lower with later updates. Stay tuned. 

Vicinity of SFO...Offshore winds will prevail through this evening,
with VFR conditions. After about 9Z, confidence becomes medium to
low, as models suggest KSFO and areas around it having 
VIS fall to MVFR. Current thinking is we may see VIS drop to 
about 6SM from 9Z-12Z with conditions potentially falling to 4SM 
from 12-17Z and then returning to VFR shortly after that period. 

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR and offshore conditions will prevail 
today and should continue into Wednesday morning. Some models 
show MVFR VIS possible after 12Z at KSNS and KMRY; however, winds
should remain elevated enough to keep fog at bay.

&&

.MARINE...
(Today through Sunday)
Issued at 858 AM PST Tue Jan 13 2026

Gentle to moderate easterly to northeasterly winds continue today,
before northerly winds return on Wednesday. Offshore winds return
Thursday and Saturday before northerlies return over the weekend.
Moderate seas will prevail through the week with the exception of
the northwestern portion of the waters where rough seas will
briefly build in Wednesday into Thursday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Bain
LONG TERM....Bain
AVIATION...KR/Behringer
MARINE...KR

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Prepared by Boulder-Creek.com Weather at: Tue Jan 13 16:30:03 PST 2026