FXUS66 KMTR 131730
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1030 AM PDT Tue Oct 13 2026

...New AVIATION...

.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

&&

.UPDATE...
Issued at 950 AM PDT Tue Oct 13 2026

Water vapor imagery shows an upper level low digging into the
Great Basin this morning, with high pressure over the Pacific. As
a result, Northern California remains situated between the two, 
with dry northerly flow aloft. Given the predominately clear
skies, cooler air, and the light winds winds, most locations saw 
morning temperatures fall into the 40s or lower 50s, with the 
coldest spots dipping into the 30s. Fall is definitely in the air. That
said, as this low shifts east, high pressure will build into the
area, with warmer conditions prevailing. Today will be the start
of that warming trend, despite the colder start to the day. Expect
temperatures to increase a few degrees each day. Overnight
temperatures will also see a minor warming trend as well this
week, but still expect the cool fall like temperatures through at
least Wednesday night. 

Periods of light to moderate offshore winds will also develop the
next several nights and continue through the early morning hours 
across the North and East Bay Mountains and Hills. While these 
gusty winds will combine with poor to moderate humidity 
recoveries, the duration and speeds should remain below red flag 
thresholds. That said, always remember one less spark. Current
forecast looks on track, so no updates are planned at this time. Palmer

&&

.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...
(18Z TAFS)
Issued at 1027 AM PDT Tue Oct 13 2026

VFR conditions will continue to persist through the TAF period as
high pressure builds in from the eastern Pacific. As such, light 
offshore winds are forecast to become onshore by early afternoon. 
Winds diminish late in the evening becoming light and variable, 
with periods of weak offshore flow overnight and into Wednesday 
morning. 

Vicinity of SFO...VFR. Onshore winds are forecast to return 
between 20Z-22Z before easing late in the evening. High 
probability for VFR conditions to prevail through the TAF period. 

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Light and variable winds are 
forecast to persist through about 21Z with onshore winds until 03Z
Wednesday. High probability for VFR conditions to prevail through
the TAF period. 

&&

.MARINE...
(Today through Sunday)
Issued at 950 AM PDT Tue Oct 13 2026

Gentle to fresh northerly breezes will continue through the 
remainder of the week with an improving seas state through 
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. 

&&

.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...RGass
MARINE...RGass

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Prepared by Boulder-Creek.com Weather at: Tue Oct 13 12:30:03 PDT 2026