FXUS66 KMTR 152036
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
136 PM PDT Thu Oct 15 2026

...New SHORT TERM, LONG TERM, FIRE WEATHER...

.KEY MESSAGES...
Updated at 1149 PM PDT Wed Oct 14 2026

 - Above normal temperatures continue into the weekend before a
   cooling trend begins Sunday into next week

 - Near critical fire weather conditions due to moderate flow and
   very dry conditions across the higher elevations Thursday and
   Friday

 - Potential for light rain and breezy onshore winds early to mid
   next week

&&

.SHORT TERM...
Issued at 132 PM PDT Thu Oct 15 2026
(This evening through Friday night)

Another warm and sunny day across our area with offshore flow 
providing above normal temperatures and abundant sunshine. With an 
upper level ridge over NorCal and upper level low over SoCal, we're 
seeing a common setup for a relatively weak Diablo wind event 
through the North Bay interior mountains, which has resulted in a 
Red Flag Warning issued for 10p tonight through 11am Friday for that 
area. The highest peaks around Mt St Helena have already seen gusts 
between 50-60 mph and we expect that to continue until winds at 
lower altitude begin to increase later tonight through late 
morning Friday. It hasn't rained in that part of the North Bay 
since September 4th, so conditions and fuels are very dry (see the
Long Term discussion below for how that may change next week). 
Elevated fire weather concerns extend beyond the Red Flag Warning 
so we continue to message to abstain from any activities that 
could ignite a wildfire. The offshore flow continues to work 
against marine layer development with some of our coastal 
locations like Half Moon Bay and Monterey already in the low 80s 
and representing some of our highest temperatures of the day so 
far.

The offshore flow will continue tonight providing clear skies 
area wide. Thermal belting above 1000ft over much of our area will
result in poor RH recovery and overnight lows well above normal, 
providing little relief from the heat until at Saturday night.

&&

.LONG TERM...
Issued at 132 PM PDT Thu Oct 15 2026
(Saturday through next Wednesday)

We expect the Red Flag warming over the North Bay interior mountains 
to expire at 11am Friday with easing winds as the mitigating factor, 
temperatures will remain warm with very dry conditions and fuels 
persisting through Saturday until a notable pattern change sets 
in on Sunday.

An upper level trough to our north will approach the coast over 
the weekend bringing a return of onshore flow, a subsequent cold 
front and notably cooler temperature and multiple days through 
the middle of next week with scattered light rain chances. We're 
not expecting any one location to see more than a 0.25", and most 
locations that see some rain will get less than a 0.10" but 
confidence is increasing that most of our area will see at least a
little bit of rainfall, with exact timing still too far out to 
speak of with any confidence.

&&

.AVIATION...
(18Z TAFS)
Issued at 1047 AM PDT Thu Oct 15 2026

High confidence for VFR conditions to prevail through the TAF 
period regionwide as high pressure builds in over the region. 
Light/variable to offshore winds prevail early this morning but 
are likely to return onshore by early-to-mid afternoon. However, 
onshore wind speeds will be weaker than previous days. 

Vicinity of SFO...VFR at the terminal through the TAF period. 
Light/variable winds persist early this morning and are forecast 
to become weak offshore and persist through about 22Z when they 
turn more onshore. Winds ease overnight and become weak offshore 
again Friday morning. Onshore winds are again forecast by Friday 
afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period. Typical 
drainage winds (southeasterly) prevail at SNS with onshore winds 
expected to return regionwide early afternoon. Winds ease after 
sunset and become light/variable overnight into Friday morning.
 

&&

.MARINE...
(Today through Tuesday)
Issued at 1047 AM PDT Thu Oct 15 2026

Moderate seas prevail across the outer waters, while the inner
waters experience slight to moderate seas through Friday night.
During this time frame, gentle to fresh northerly breezes
continue. Moderate to fresh northerly winds return for the
weekend, which will be accompanied with rough seas.

&&

.FIRE WEATHER...
Issued at 132 PM PDT Thu Oct 15 2026

A Red Flag Warning was issued for the North Bay Interior 
Mountains that goes into effect at 10PM tonight and runs through 
11AM Friday morning. This is due to moderate offshore winds very 
dry with very poor overnight humidity recoveries only reaching 15 
to 25 percent. Rapid fire spread is possible given the 
combination of gusty northerly winds and very dry overnight 
conditions.

Elsewhere in the Bay Area, elevated to near critical fire weather
conditions continue for the higher elevations late tonight 
through Friday morning. Dry conditions, poor overnight RH 
recovery, combined with the breezy winds, warmer weather, and 
available fuels leads to the elevated to near critical fire 
weather conditions. 

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning from 10 PM this evening to 11 AM PDT Friday for 
     CAZ504.

PZ...None.
&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...RGass
MARINE...RGass

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 15 14:30:02 PDT 2026