FXUS66 KMTR 172040
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
140 PM PDT Sat Oct 17 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 139 PM PDT Sat Oct 17 2026
- Very warm temperatures continue today
- Hazardous beach conditions through at least this weekend
- Much cooler weather arrives Sunday with rain chances midweek
&&
.SHORT TERM...
Issued at 139 PM PDT Sat Oct 17 2026
(This evening through Sunday night)
This afternoon is shaping up to be another very warm day with
temperatures reaching into the upper 80s to low 90s across the
interior, around the Santa Cruz region, and Monterey Bay region.
Temperatures reached the low 90s around Monterey region as onshore
flow was delayed. However, the onshore flow has returned cooling
temperatures into the upper 70s to mid 80s. The immediate
coastline is forecast to remain in the low-to-upper 70s. That
said, the high pressure over northern California is weakening and
will continue to do so through the remainder of the weekend.
The cooling trend will be more robust tonight and into Sunday as
a dry frontal boundary moves across the Bay Area and north Central
Coast. This will also allow for a slightly stronger onshore flow
and deepening marine layer (albeit temporarily) and more
seasonable temperatures. Thus, temperatures will be some 10-15
degrees or more cooler than today.
&&
.LONG TERM...
Issued at 139 PM PDT Sat Oct 17 2026
(Monday through next Friday)
A more robust cool down will occur Monday as the upper-level
trough deepens off of the West Coast, bringing temperatures to
below seasonal averages. The trough becomes a cut-off low by
Tuesday with its center approximately 350 miles west of San
Francisco. This will bring a cold front through the region Monday
night into Tuesday morning as the center of the low pressure
system pushes inland across the south Central Coast and/or
southern California Wednesday evening into Thursday. This will
result in unsettled weather conditions across the region Tuesday
through Thursday.
As far as precipitation and thunderstorm chances go, there is a
20- 40% chance of rain showers across the greater Bay Area and
30-60% chance across the Central Coast. The greatest potential for
convection is now on Wednesday when the core of the low begins to
move onshore. The greatest potential (generally 15% or less) will
be over the offshore waters and Central Coast where the greatest
instability will be located.
A further offshore and southern track of the low pressure system
would result in less rainfall and lower probability for
convection. However, if it were to move directly into the Central
Coast (or even the Bay Area) we would have stronger winds, heavier
rain, and increased potential for thunderstorms. Thus, be sure to
check back on the forecast as the event draws nearer.
&&
.AVIATION...
(18Z TAFS)
Issued at 1002 AM PDT Sat Oct 17 2026
Currently VFR. Moderate confidence on LIFR conditions returning
to the coastal terminals of HAF, MRY, and SNS tonight. The
atmosphere will need to undergo a lot of change over the next 18
hours for this to happen coming off of hot and dry conditions with
no marine layer. Upstream observations show some stratus and fog,
but a pattern change with an increase in wind and mixing will
likely make it more difficult for the marine layer to reform.
Diurnal winds will prevail. Haze will reduce slant range
visibilities.
Vicinity of SFO...Currently VFR with northerly flow. High
confidence in VFR through the TAF period. Northerly flow will back
through the morning to become westerly with the sea breeze this
afternoon.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Currently VFR with southwesterly flow at
MRY and VFR with southeasterly flow at SNS. Moderate confidence
on LIFR conditions returning to the terminals tonight. Diurnal
winds will prevail.
&&
.MARINE...
(Today through Thursday)
Issued at 1002 AM PDT Sat Oct 17 2026
Moderate to fresh northwesterly breezes will prevail through
Monday with strong breezes across the northern outer waters.
Widespread hazardous conditions will spread across the coastal
waters as a result Sunday afternoon, likely continuing into
Monday. Moderate seas will prevail across the inner waters with
rough seas building across the outer waters Saturday through
Monday, rebuilding again Tuesday. Light rain is expected Monday
night through Wednesday.
&&
.BEACHES...
Issued at 1002 AM PDT Sat Oct 17 2026
Hazardous beach conditions will be present at Pacific Coast beaches
through Sunday and likely into next week. Long period
southerly/southwesterly swell will bring an increased risk for
sneaker waves and strong rip currents with breaking waves of 7 to 12
feet. Remain off jetties, piers, rocks, and other waterside
infrastructure as waves can sweep across the shoreline without
warning, pulling people into the sea. Remain out of the water to
avoid hazardous surf with strong rip currents and never turn your
back on the ocean!
Sarment
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Sunday evening for CAZ006-505-
509-529-530.
PZ...Small Craft Advisory from 3 AM to 9 PM PDT Sunday for Pt Arena
to Pt Reyes 0-10 nm.
Small Craft Advisory from 3 PM to 9 PM PDT Sunday for Pigeon Pt
to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Pinos
to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 PM PDT Sunday for Pt Arena to Pt
Reyes 10-60 NM.
&&
$$
SHORT TERM...RGass
LONG TERM....RGass
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: Sat Oct 17 16:30:03 PDT 2026
From the National Weather Service
|