FXUS66 KMTR 090657
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1157 PM PDT Thu Oct 8 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 927 PM PDT Thu Oct 8 2026
- Sharp cool-down this weekend and early next week
- Coastal flooding during high tides and large swell this weekend
- Beach Hazards Saturday morning until Monday afternoon
- Light rain possible north Central Coast early next week
&&
.SHORT TERM...
Issued at 1157 PM PDT Thu Oct 8 2026
(Tonight through Saturday)
Coastal stratus will be on the increase tonight and Friday
morning. The onshore SFO-SAC pressure gradient has increased to
2.5 mb. Strong thermal ridging aloft, a compressed marine layer
combining with daily solar input resulting in well above normal
October temperatures has essentially reached its peak. Inland
daytime high temperatures will still be warm Friday, but closer
to 30 year (1991-2020) normal highs for October 9th.
Later Friday, Friday night and especially Saturday northwest winds
will result in cold air advection. A major pattern shift will usher
in strong upper level troughing i.e. much cooler air arriving here
Saturday. The marine layer lower level temperature inversion will
fully erode Saturday allowing plenty of vertical mixing. This pattern
shift will bring a noticeable cool down, especially for inland
areas.
&&
.LONG TERM...
Issued at 1157 PM PDT Thu Oct 8 2026
(Saturday night through next Thursday)
Much cooler air from the surface to aloft continues to arrive
Sunday. The strong cold core 500 mb low will sweep southward over
our coastal waters with land overlap, resulting in gusty winds
over the coastal waters and areas of gusty winds over land as
well over the weekend. There's limited moisture availability with
the low arriving from the north and a solid southerly push of
drier air and lower precipitable water values on the back side of
the low will mainly influence our forecast area over the weekend
and early next week. The depth of cold air with the low of course
will be passing over increasing sea surface temperatures as it moves
south, which may produce showers over the southern forecast area
early next week. 500 mb high pressure ridging will then move in
from the west with dry weather and an uptrend back to near mid
October normal temperatures.
&&
.AVIATION...
(06Z TAFS)
Issued at 1003 PM PDT Thu Oct 8 2026
VFR everywhere except for HAF, MRY, and SNS where LIFR-IFR
conditions prevail through Friday morning. Fog development is
possible overnight at these sites, including STS, though low to
medium confidence on the exact timing. Overnight, winds remain light
and gradually increase to a moderate onshore breeze Friday afternoon
with locally stronger winds at SFO. The anticipated cold frontal
passage is complicating the ceiling forecast tonight and Friday
evening. The marine layer will deepen, but it will likely remain too
shallow to reach the interior East and South Bay valley terminals.
Moderate confidence for IFR ceilings at OAK and LIFR ceilings at the
coastal sites plus STS.
Vicinity of SFO...VFR. Northwest winds gradually ease overnight. Low
confidence on stratus impacts at SFO with scattered decks more
likely. OAK continues to have a higher chance of borderline IFR-MVFR
ceilings that will mix out by late Friday morning. Northwest winds
increase that afternoon and remain elevated through the evening as
the cold front passes through the region.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...IFR ceilings will gradually drop to LIFR
overnight, resulting in foggy/misty conditions through Friday
morning. Low to medium confidence on the exact timing of visibility
reductions. VFR prevails Friday afternoon once onshore winds
increase to around 10 kt. IFR ceilings are likely to return around
sunset again on Friday.
&&
.MARINE...
(Tonight through next Wednesday)
Issued at 1003 PM PDT Thu Oct 8 2026
Hazardous marine conditions begin Friday through the weekend.
North to northwesterly breezes increasingly become strong to near
gale force as a cold front approaches the coast. Very rough wind
driven seas build up to 15 feet with a low long period southerly
swell arriving on Friday, which is then replaced by a moderate
rough long period westerly swell on Sunday. Marine conditions
gradually improve early next week as northwest winds ease.
&&
.FIRE WEATHER...
Issued at 428 AM PDT Thu Oct 8 2026
Hot and dry conditions will lead to elevated fire weather conditions
across the interior and higher terrain Thursday. Temperatures 10 to
20 degrees above normal and poor minimum relative humidity will
continue away from the compressed marine layer at the coast
Thursday. The higher terrain will experience active thermal belting,
little-to-no recovery with nocturnal drying across the highest
peaks, and thus prolonged burn periods. Winds remain the limiting
factor, with diurnal winds prevailing except for light
northerly/offshore flow overnight across the higher terrain. Even
though conditions become cooler and more humid Friday, windier
conditions will keep elevated fire weather conditions across the
interior and higher terrain through Friday.
Sarment
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory from 9 AM Friday to 3 PM PDT Tuesday for
CAZ006-508-529-530.
Beach Hazards Statement from Saturday morning through Monday
afternoon for CAZ006-505-509-529-530.
Coastal Flood Advisory until 4 PM PDT Wednesday for CAZ506.
PZ...Small Craft Advisory from 3 PM Friday to 3 AM PDT Saturday for
Pt Arena to Pt Reyes 0-10 nm-SF Bay N of Bay Bridge.
Small Craft Advisory from 3 AM Friday to 3 AM PDT Saturday for
Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory from 9 PM Friday to 3 AM PDT Saturday for
Pigeon Pt to Pt Pinos 10-60 NM.
&&
$$
SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...Navarrete
MARINE...Navarrete
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Prepared by Boulder-Creek.com Weather at: Fri Oct 9 04:30:03 PDT 2026
From the National Weather Service
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