FXUS66 KMTR 151749
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1049 AM PDT Thu Oct 15 2026
...New AVIATION, MARINE...
.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
&&
.UPDATE...
Issued at 821 AM PDT Thu Oct 15 2026
No update to the forecast necessary this morning. A Fire Weather
Watch was issued overnight for the North Bay interior mountains
where very dry and windy conditions tonight through Friday morning
will promote rapid spread of any fire ignitions. Winds at the
highest spots are already sustained at 30+ MPH with little to no
overnight relative humidity recovery last night. RH values this
morning are generally in the 20-30% range, and expected to be in the
teens by later today. The decision on whether to upgrade to a Red
Flag Warning will be made this afternoon with the scheduled forecast
update. There are pockets of moderate HeatRisk this afternoon with
the warming temperatures, mainly in the North Bay and East Bay. More
widespread HeatRisk is in store for Friday, including many coastal
areas as offshore flow continues to work against the marine layer.
&&
.SHORT TERM...
Issued at 1149 PM PDT Wed Oct 14 2026
(Tonight through Friday)
Near critical fire weather conditions continue across the higher
elevations, particularly the North Bay Interior Mountains, through
Friday. A positively tilted upper level ridge remains over Oregon
and Northern/Central California while a cut-off low lingers over
Southern California. This setup promotes light to moderate offshore
winds across the region with the potential for more moderate to
gusty offshore winds across the higher elevations. Model guidance
keeps gusts across the elevated terrain peaking between 20 to 30 mph
with locally stronger gusts possible across the highest peaks (e.g.
Mt. St. Helena). The GFS and HRRR are both in agreement that the SFO-
WMC gradient will peak around -9 mb Thursday morning and -10 mb
Thursday night into Friday. The NAM continues to be an outlier and
suggests the gradient could peak around -14 mb but looking closer
into their forecast wind gusts still keeps gusts in a similar, but
slightly stronger range, of 25 to 35 mph. Very dry conditions are
expected across the higher elevations during both the daytime and
overnight hours. Much of the region will see daytime RH in the 10s
to 20s with poor to very poor overnight recoveries with the worst
recoveries across the higher elevations. Given the very dry
conditions and potential for offshore winds, any spark has the
potential to start a fire. Remember, one less spark one less
wildfire.
Warmer temperatures continue Thursday and Friday with highs in the
80s to low 90s on Thursday and upper 80s to 90s on Friday. Patchy
Moderate HeatRisk is expected on Thursday but becomes more
widespread across urban areas on Friday. If you are outdoors during
peak heating, make sure you are drinking plenty of water and taking
frequent breaks in the shade. The marine layer remains mixed out
through the short term due to the presence of the ridge so expect
&&
.LONG TERM...
Issued at 1149 PM PDT Wed Oct 14 2026
(Friday night through next Wednesday)
Offshore winds decrease by Friday afternoon/evening as upper level
ridging weakens and broad troughing returns to the region. High
temperatures Saturday will still be warm in the 80s to low 90s but
cooler temperatures return Sunday into next week. By Sunday, broad
troughing returns to the region with temperatures cooling into the
70s to low 80s. Fall weather returns in force next week as we get
our first potential rainmaker of the season. This low pressure
system looks to originate from the Gulf of Alaska and will bring
much cooler, moister air into the region as the surface low weakens
and moves into California next week. Highs will be seasonal to below
normal in the 60s to low 70s across the interior and upper 50s to
low 60s along the coast. Rain chances increase Tuesday through
late week with wetting rains (>0.10") likely across the Central
Coast and potentially Santa Cruz County/the South Bay. Light rain
is possible across the rest of the Bay Area but does not look to
meet wetting rain criteria at this time. Guidance is showing a low
(<10%) chance of thunderstorms next week so that will be
something to keep an eye on as this event gets closer in time. &&
&&
.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 547 AM PDT Thu Oct 15 2026
A Fire Weather Watch was issued for the North Bay Interior
Mountains and will go into effect later this evening and run
through Friday morning. This is due to moderate offshore winds
very dry with very poor overnight humidity recoveries only
reaching 14 to 24 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 are expected 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...Fire Weather Watch from 10 PM PDT this evening through Friday
morning for CAZ504.
PZ...None.
&&
$$
SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...RGass
MARINE...RGass
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Prepared by Boulder-Creek.com Weather at: Thu Oct 15 12:30:03 PDT 2026
From the National Weather Service
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