FXUS66 KMTR 131135
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
435 AM PDT Tue Oct 13 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1119 PM PDT Mon Oct 12 2026
- Fall weather continues today; warming trend and above normal
temperatures starting mid to late week
- Coastal flooding during high tides through midweek
- Elevated fire weather conditions and offshore flow across the
higher elevations peaking mid to late week
&&
.SHORT TERM...
Issued at 1119 PM PDT Mon Oct 12 2026
(Tonight through Wednesday)
Expect one more cooler taste of fall on Tuesday before a warming
trend starts off Wednesday. Upper level troughing will gradually
shift eastward Tuesday into Wednesday with upper level ridging
building in Wednesday. The marine layer remains mixed out through
the short term with clear skies expected across the majority of the
area with only patchy clouds expected along the coast. Clear skies
will lead to increased radiational cooling and see chillier mornings
in the 40s to low 50s returning again Tuesday and Wednesday
mornings. Portions of the higher elevations will dip into the 30s
but this will be more widespread on Tuesday than on Wednesday as a
warming trend begins. Daytime highs on Tuesday will be in the 60s to
mid 70s with further warming into the 70s to low 80s across the
interior expected on Wednesday as the ridge rebuilds. Coastal
temperatures stay fairly consistent in the upper 50s to 60s.
Worth noting is the potential for multiple rounds of offshore winds
in the overnight to late morning hours starting tonight and
continuing through the week. Offshore winds look to be the strongest
across the Interior North Bay Mountains and along the Diablo Range
in the East Bay and South Bay. The SFO-WMC gradient suggests rounds
of overnight offshore winds Monday night and Tuesday night will be
light to moderate with the gradient peaking around -3 to -4.5 mb.
The gradient is expected to strengthen late week as additional
rounds of offshore winds occur (see Long Term discussion).
Elevated fire weather conditions are expected across the higher
elevations given the moderate pulses of offshore winds, dry
conditions, and poor overnight recoveries.
&&
.LONG TERM...
Issued at 1119 PM PDT Mon Oct 12 2026
(Wednesday night through next Monday)
Temperatures continue to warm Thursday and Friday as upper level
ridging builds. High temperatures will peak in the upper 80s to low
90s with pockets of mid to upper 90s across the Santa Cruz Mountains
and southern Santa Clara Valley. Patchy Moderate HeatRisk is
expected on Thursday with more widespread Moderate HeatRisk across
urban areas on Friday. Although not the hottest temperatures we've
seen this summer, Moderate HeatRisk makes its return due to
overnight lows creeping back into the 50s to low 60s. Not a fan of
the heat? Good news, temperatures start to cool again Saturday and
Sunday as upper level ridging is disrupted by a cut-off low to our
south. This cut-off low will rejoin the jet stream, deepening upper
level troughing over the West Coast, and bring cooler weather back
to the region. High temperatures drop into the 80s across the
interior on Saturday before more fall like weather in the 60s to 70s
returns Sunday and Monday. Model guidance indicates there is some
potential for light rain (few tenths of an inch) and strong onshore
winds early next week as the trough moves through. This will bring a
return of hazardous marine conditions and strong winds to mountain
gaps and passes and the higher terrain.
Elevated fire weather concerns continue across the higher elevations
through late this week as additional rounds of offshore flow are
expected overnight through the late morning. These pulses of
offshore winds look to strengthen overnight Wednesday into
Thursday. The GFS shows an initial forecast for the SFO-WMC
gradient to reach -9.6 mb late Thursday morning. Offshore flow is
likely again Thursday night into Friday morning but it looks to be
weaker than the previous night. If you are engaging in any
activities involving fire, prevent any flames/sparks from
escaping as the fuels are dry and conditions will be favorable for
fire to spread.
&&
.AVIATION...
(12Z TAFS)
Issued at 429 AM PDT Tue Oct 13 2026
VFR. Weak offshore flow and a dry airmass are yielding small
pockets of stratus that have occasionally resulted in brief MVFR
ceilings overnight but VFR will prevail through the forecast
period.
Vicinity of SFO...VFR. No marine layer influence with weak
offshore flow, will maintain VFR conditions through the forecast
period.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR is expected to prevail through the
forecast period with weak offshore flow and little to no marine
layer influence.
&&
.MARINE...
(Today through Sunday)
Issued at 429 AM PDT Tue Oct 13 2026
Gentle to fresh northerly breezes will continue through the
remainder of the work week with an improving seas state today into
Wednesday. Long period southerly swell will also continue through
midweek with some gradual easing by the end of the week.
&&
.FIRE WEATHER...
Issued at 118 PM PDT Mon Oct 12 2026
There will be a few bursts of offshore winds this week, generally
during the overnight hours. The first burst looks to occur tonight,
particularly highlight the interior North Bay Mountains, where we
could see gusts range from 20-35 mph, perhaps even up to 40 mph for
the exposed ridges and the higher elevations. After that, the next
area of concern we are monitoring is Wednesday night into Thursday
morning, where the pressure gradient should be a bit more tight due
to upper level wind patterns. Majority of the area should see
offshore flow, in the north to northeast component, with gusts
closer to 25-35 mph, locally higher perhaps up to 45 mph for
exposed ridges, gaps, and passes. Warm and dry weather will be on
tap as well, which will lead to an elevated threat for the higher
terrain areas. Another round of offshore winds is expected
Thursday night into Friday, but appears to be weaker than the
previous two.
&&
.BEACHES...
Issued at 1031 AM PDT Mon Oct 12 2026
Compare to the last few days conditions along the coast are
gradually improving as longer period swell trains are decreasing.
However, buoy reports Monday morning continue to advertise
moderate to longer period swells (albeit smaller heights)
entering the coastal waters. As such, elevated surf zone
conditions lingering. Additionally, moderate period west-northwest
swell will arrive Monday afternoon lingering into Monday evening.
As such, Beach Hazard Statement remains in effect through this
evening. The large tidal swings will also result in coastal
erosion as water and waves are brought farther up the beach than
normal, especially during high tide. Remain off jetties, piers,
rocks, and other waterside infrastructure as waves can sweep
across the shoreline without warning, pulling people into the sea.
Never turn your back on the ocean!
MM
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 3 PM PDT this afternoon for CAZ006-
508-529-530.
Coastal Flood Advisory until 4 PM PDT Wednesday for CAZ506.
PZ...None.
&&
$$
SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...JM
MARINE...JM
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Prepared by Boulder-Creek.com Weather at: Tue Oct 13 06:30:04 PDT 2026
From the National Weather Service
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