FXUS66 KMTR 081130
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
430 AM PDT Thu Oct 8 2026
...New AVIATION, MARINE, FIRE WEATHER...
.KEY MESSAGES...
Updated at 1259 PM PDT Wed Oct 7 2026
- Hot inland temperatures continue Thursday
- Sharp cool-down this weekend and early next week
- Coastal flooding during high tides and large swell this
weekend
- Light rain possible early next week
&&
.SHORT TERM...
Issued at 1155 PM PDT Wed Oct 7 2026
(Tonight through Sunday)
Strong 500 mb high pressure ridging bringing inland areas hot
and dry weather will continue into Thursday. Well above early
October normal temperatures occurred again today, though none of
the long term stations set any new record highs today. The Heat
Advisory (WMO header WWUS76) for inland areas continues through
10 pm PDT Thursday. And a reminder there is a Coastal Flood
Advisory (WHUS36) for anomalous high tides with up to 1.2 feet of
inundation above ground level in low-lying areas.
As mentioned it'll be hot again inland Thursday while cooler
temperatures will prevail along the immediate coastline within a
compressed marine layer. NBM forecast highs were nudged downward
slightly for much of the immediate coastline for Thursday. Global
models continue to indicate a major pattern shift will take place
over the western states beginning later tomorrow through Friday.
A weak 500 mb low ~ 900 miles to our west will progress toward our
forecast area allowing part of the aforementioned 500 mb high
pressure ridge to slip westward (retrogressing) far to our west.
Separate strengthening 500 mb troughing will take place over the
Pacific Northwest; long wave troughing will begin to replace long
wave ridging over the west. Mid-latitude amplification and winds
will move the 500 mb trough southward, decidedly shifting the pattern
south and east including the near term weak 500 mb low just out
ahead of it and the rest of the 500 mb ridge. This pattern shift
will bring in much cooler air from the surface up through 500 mb
across the forecast area through the weekend.
Winds will become gusty over the coastal waters and gap winds will
increase as well during the weekend, both Saturday and perhaps Sunday
with gusts possibly nearing wind advisory level in the usual wind
favored gaps across the San Francisco Peninsula and the East Bay.
&&
.LONG TERM...
Issued at 1155 PM PDT Wed Oct 7 2026
(Sunday night through next Wednesday)
Winds over land diminish later Sunday. There may be some residual
moisture the cold core low will tap producing a few showers over
the southern forecast area later Sunday and Monday. Otherwise dry
and much cooler weather is forecast later Monday, Tuesday and
Wednesday. Daytime highs and lows will shift to below normal.
Daytime highs will generally be in the 60s coast to the 70s
inland. Night-time and morning lows will mostly be in the 40s
except around 50 at the coast and as cold as the 30s far inland
valleys.
&&
.AVIATION...
(12Z TAFS)
Issued at 428 AM PDT Thu Oct 8 2026
Currently LIFR-VFR. Dense fog has been observed at the coastal
terminals of HAF, MRY, and SNS as well as STS overnight. An otter
eddy will complicate things around the Monterey Bay, but generally
high confidence in fog continuing through 16Z for the coastal
terminals. STS has a shallow fog layer, but will still keep them
prevailing fog through 16Z with at least 3 more hours of radiational
cooling to go. Low confidence in fog reaching bayshore or interior
terminals this morning. The marine layer is expected to deepen
tonight, bringing increased (40-50%) chances for sub-VFR conditions
at bayshore and interior terminals. Right now, it looks like it
would be IFR and occur at the end of the current TAF period/into the
next one. Diurnal winds will prevail.
Vicinity of SFO...Currently VFR with northwesterly flow. Moderate
confidence on VFR and diurnal winds prevailing through the TAF
period. With a deepening marine layer Thursday night, farther inland
intrusion is expected. Stratus will likely make it through the
Golden Gate Gap by 09Z, spreading north and south along the East Bay
Hills, creating a donut hole around the terminal.
SFO Bridge Approach...Low probability for LIFR/IFR radiative stratus
to develop around NUQ/SJC this morning. If it forms, it'll likely be
short-lived with conditions improving by 16Z and clear skies by the
afternoon. Moderate confidence on the San Mateo Bridge Approach
being impacted Friday morning. It will likely be a combination of
advective and radiative stratus with the most likely spots along the
East Bay Hills and between SQL and SJC. Conditions will begin to
improve by 16Z with clear skies expected by the afternoon.
Monterey Bay Terminals...Currently LIFR and calm at both terminals.
An otter eddy in the Monterey Bay will keep fog around through at
least mid-morning with conditions beginning to improve by 16Z.
Persistence forecast on tap tonight with an early return of LIFR
ceilings by 03Z and fog at 09Z. Diurnal winds will prevail.
&&
.MARINE...
(Today through Tuesday)
Issued at 428 AM PDT Thu Oct 8 2026
Moderate to fresh northwesterly breezes and moderate seas will
prevail Thursday. Conditions deteriorate Friday and into the
weekend as northerly breezes increase to become strong to near
gale across the coastal waters, Monterey Bay, and through the
Golden Gate Gap. Gale force gusts can be expected across the
northern outer waters and the coastal jet region of Point Reyes.
These winds will build rough to very rough seas. Long period
southerly swell arrives Friday, with long period northwesterly
swell arriving Sunday this will create a confused sea state.
&&
.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.
Heat Advisory until 10 PM PDT this evening for CAZ503-504-506-
508-510-512>518.
Coastal Flood Advisory until 4 PM PDT Wednesday for CAZ506.
PZ...Small Craft Advisory from 3 AM to 3 PM PDT Friday for Pt Arena
to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...Sarment
MARINE...Sarment
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: Thu Oct 8 08:30:03 PDT 2026
From the National Weather Service
|