FXUS66 KMTR 101124
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
424 AM PDT Thu Sep 10 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1201 AM PDT Thu Sep 10 2026
- Widespread moderate HeatRisk continues today
- Cooler temperatures, closer to seasonal averages, Friday into
the weekend
&&
.SHORT TERM...
Issued at 1201 AM PDT Thu Sep 10 2026
(Today and tonight)
Temperatures were very hot yesterday, with four daily records broken
and temperatures in the lower to middle 80s persisting well into the
evening for much of the Bay Area and Central Coast. Scattered high
clouds stemming from the remnants of Tropical Storm Marie
continue to impact the the SF Bay Area, inhibiting the radiational
cooling impacts. The morning lows have been bumped up as a
result, and range from the middle 60s to lower 70s for the
immediate Pacific Coast and areas close to the Bays, into the
middle to upper 70s for the inland valleys, and the lower 80s for
the highest ridgelines. Confidence in the forecast is moderate and
the temperatures could drop lower if radiational cooling is more
robust than currently expected.
The strong high pressure system from the Desert Southwest that drove
yesterday's scorching temperatures will stick around for today,
but through the day a pulse of energy from northwestern Canada
will descend and reinforce a trough over British Columbia and the
Pacific Northwest. This will begin the process of flattening the
ridge and while the high temperatures will still be dangerously
warm, they will likely be cooler than yesterday's with the inland
valleys reaching highs in the 90s, into the triple digits for the
warmest interior locations, and the middle 70s to the upper 80s
for the Bayshore regions. There is some uncertainty over how the
temperatures will develop at the Pacific coast, where the
flattening ridge should allow for some stronger onshore flow to
develop, but the current forecast shows these areas around the
upper 60s to middle 70s, possibly higher if the onshore breeze
does not develop. By the evening hours, a marine layer should
begin to redevelop, allowing low clouds to return to the immediate
coast.
Widespread moderate HeatRisk continues today, corresponding to a
moderate risk of heat-related illnesses for sensitive populations,
while favored locations including interior Contra Costa County and
the Santa Lucia range remain in major HeatRisk, corresponding to a
major risk for heat related illnesses for most people. Please
remember these tips to help mitigate impacts from heat exposure:
-Suspend unnecessary outdoor activities during the extreme heat, but
if you must be outdoors, take frequent breaks in the shade or AC
and drink cool water.
-Know the signs and symptoms of Heat Exhaustion vs. Heat Stroke!
Heat Stroke can be deadly if not treated immediately by a medical
professional. Call 911 if you suspect someone is suffering from Heat
Stroke.
-Wear a life jacket, swim near a lifeguard, and check conditions
before entering the water if going to a river or ocean to cool off.
Rivers and the ocean are extremely cold, and Cold Water Shock can
turn into paralysis and drowning if you are not careful.
-Use a cool and damp towel on your body if you do not have AC and
are feeling hot. Or, take a cool shower or bath.
-Do not leave kids or pets in a parked car.
-Ensure pets and livestock have access to shade and water.
&&
.LONG TERM...
Issued at 1201 AM PDT Thu Sep 10 2026
(Friday through Wednesday)
The cooling trend continues Friday into the weekend as the pulse of
energy breaks off into its own cutoff low off the coast of British
Columbia and strengthens as it parallels the Pacific Northwest
coast, allowing for further development of the onshore flow and
marine layer to take place. By the weekend, highs will drop into the
middle 70s to middle 80s inland and the upper 60s to upper 70s close
to the Bays. The SFO-WMC pressure gradient rises to around 12 to 15
mb on Saturday, suggesting the possibility for strong onshore winds.
The trough axis should move into the northern Rockies and the
northern Plains for the early part of next week, but the general
pattern should remain rather zonal for the remainder of the 7-day
outlook, and temperatures should remain more or less stable.
&&
.AVIATION...
(12Z TAFS)
Issued at 359 AM PDT Thu Sep 10 2026
VFR conditions under scattered high clouds will persist through
the afternoon. The onshore gradient has returned, however. There
will be a moderate sea breeze in the afternoon, and the marine
layer will likely start to reform Thursday evening. Coastal
terminals are likely to see ceilings return by Friday morning.
Vicinity of SFO...VFR conditions will very likely persist through
the day. A sea breeze will return this afternoon with sustained
winds to 15 kt likely. As the marine layer returns, there is a
good chance for IFR or MVFR ceilings to reach the terminal before
sunrise Friday morning.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...High confidence in VFR conditions through
the day with moderate onshore winds in the afternoon. As the
marine layer reforms overnight, MRY has a 70% of at least MVFR
ceilings, and SNS has a 50% chance Friday morning.
&&
.MARINE...
(Today through Tuesday)
Issued at 359 AM PDT Thu Sep 10 2026
A moderate NW breeze and moderate seas will persist today. Winds
will increase over the next 48 hours, with a fresh to strong NW
breeze expected this weekend. A moderate SW swell from distant
tropical cyclones will continue into early next week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 10 PM PDT this evening for CAZ006-502>506-
508>510-512>518-528>530.
PZ...Small Craft Advisory from 3 AM to 9 PM PDT Friday for Pt Arena
to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory from 9 AM to 9 PM PDT Friday for Pigeon Pt
to Pt Pinos 0-10 nm.
Small Craft Advisory from 3 PM this afternoon to 9 PM PDT Friday
for Pt Pinos to Pt Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Flynn
MARINE...Flynn
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Prepared by Boulder-Creek.com Weather at: Thu Sep 10 04:30:03 PDT 2026
From the National Weather Service
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