FXUS66 KMTR 050502
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1002 PM PDT Sun Oct 4 2026
...New UPDATE...
.KEY MESSAGES...
Updated at 1213 PM PDT Sun Oct 4 2026
- Warm to hot conditions across the region through mid-week
- Hazardous heat conditions expected to persist inland, never
leave children or pets in unattended vehicles!
- Elevated fire weather conditions persist in the interior
through Thursday
&&
.UPDATE...
Issued at 1002 PM PDT Sun Oct 4 2026
Despite the hot temperatures across our region today no records
were broken this afternoon/evening. The area of high pressure over
our area coupled with offshore flow will keep temperatures well
above normal through the middle of the week. The Heat Advisory for
areas close to the Pacific Coast from Sonoma County to Santa Cruz
County has been allowed to expire, however for the Big Sur
coastline and the remainder of our interior locations, the Heat
Advisory continues through Wednesday. Monday temperatures near the
coast will be a few degrees cooler than Sunday, but still above
normal, across the interior we'll see temps close to or slightly
above what was realized earlier today.
&&
.SHORT TERM...
Issued at 1213 PM PDT Sun Oct 4 2026
(This evening through Monday night)
It's hot. A persistent ridge over the western United States keeps
the area much above the seasonal average (15 to 25 degrees above
seasonal average away from the immediate coast). As of 11 AM today
temperatures across the region ranged from the 80s into the lower
90s inland, the 70s to the lower 80s close to the Bays, and the
middle 60s to the middle 70s for the Pacific coast. There are some
high clouds flowing above the SF Bay Area, but they do not seem to
be impacting the heat levels. High temperatures today and Monday
will be rather similar in the inland valleys, ranging from the
middle 90s to near 104. Closer to the Bays, today's highs will be in
the middle 80s to the middle 90s while locations along the Pacific
coast rise into the 70s. Across the higher elevations and some
nearby valleys, especially in the East and South Bays, mild
overnight lows in the upper 60s to middle 70s will limit the
ability to recover overnight. For Monday, these temperatures are a
little uncertain owing to potential impacts from a shallow marine
layer or a marginally stronger onshore flow than the current
forecast, but highs should remain in the 70s and 80s. If confidence
in highs towards the higher part of that range increases, the Heat
Advisory for our coastal regions may need to be extended.
Due to the hazardous heat levels, a Heat Advisory is in effect for
coastal locations through 10 PM tonight, while inland and Bayshore
areas remains under the Advisory through Wednesday. Widespread
Moderate HeatRisk blankets the region, corresponding to a moderate
risk of heat-related illnesses for sensitive populations, including
children, the elderly, pregnant women, people with chronic
illnesses, and people who work or live outdoors without access to
adequate cooling or hydration. In addition, many of the higher
elevations in addition to the East Bay, South Bay, and the Carmel,
Hollister, and northern Salinas Valleys see Major HeatRisk,
corresponding to a high risk for heat-related illnesses for anyone
without hydration or cooling. Follow these tips to avoid heat
exhaustion and heatstroke:
* Stay hydrated and drink plenty of fluids.
* Wear lightweight, light-colored clothing.
* Reduce time spent outdoors or stay in the shade.
* Never leave people or pets unattended in vehicles.
* Use sunscreen if going to the coast or the pool.
&&
.LONG TERM...
Issued at 1213 PM PDT Sun Oct 4 2026
(Tuesday through next Saturday)
The ridging persists for the next few days and as previously
mentioned, the Heat Advisory extends to Wednesday night for the
inland and Bayshore regions. Temperatures across the inland valleys
remain in the middle 90s to near 105 through Wednesday. Along the
Pacific, we continue to monitor how the forecast trends evolve as
impacts from a shallow marine layer or stronger onshore flow than
the current forecast may significantly impact the immediate coast.
A pattern change will begin Thursday as the ridge flattens and
troughing develops in the northeastern Pacific and moves into
southwestern Canada and the western United States. This will start a
cooling trend with most locations dropping out of Moderate HeatRisk
by Friday. Ensemble model cluster analysis hints at significant
uncertainty for the upcoming weekend and the early part of the
upcoming week regarding the strength of the trough and how long it
could persist.
&&
.AVIATION...
(06Z TAFS)
Issued at 944 PM PDT Sun Oct 4 2026
Confidence is mixed as to if stratus/fog will make it to the
coastline tonight. Kept the stratus mention in for HAF but
confidence is decreasing in fog reaching MRY and SNS. Diurnally
breezy winds continue with moderate onshore winds during the day
and light, variable winds overnight.
Vicinity of SFO...VFR. Diurnally breezy winds with moderate west
to northwest winds around 16 knots expected during the day before
winds weaken overnight.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Mixed confidence as to if stratus/fog
will reach MRY and SNS tonight. Models are currently
overestimating the eastward extent of the offshore stratus (i.e.
placing it closer to shore) while observations show the stratus
deck to still be well offshore. This is decreasing confidence in
CIG development along the Monterey Peninsula. The wrinkle in this,
however, is that clear skies across the peninsula will allow for
additional radiational cooling and see temperatures dropping
closer to the dewpoint. This would increase the likelihood of fog
development and LIFR conditions. Leaned towards VFR conditions
continuing tonight with some potential for fog to develop early
Monday morning.
&&
.MARINE...
(Tonight through next Saturday)
Issued at 944 PM PDT Sun Oct 4 2026
A gentle to moderate breeze and slight to moderate wave heights
persist into midweek. Winds increase and wave heights build, seas
becoming rough across the outer waters, Friday into the weekend.
&&
.FIRE WEATHER...
Issued at 405 AM PDT Sun Oct 4 2026
Hot and dry conditions will continue through Thursday, which will
be accompanied with weak offshore flow. Poor to very poor
overnight recovery is expected for the thermal belts, generally
for elevations above 1000-1500 feet, leading to elevated fire
weather conditions. The marine layer is expected to be confined to
the immediate coast and around 500 feet. If working in the
thermal belts, Moderate to Extreme HeatRisk is forecast this week,
with temperature and HeatRisk trends improving late week. A
pattern change is expected late in the week or over the weekend.
Cooler weather and the potential for improved RH recovery is
forecast or Friday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 10 PM PDT Wednesday for CAZ503-504-506-508-
510-512>518.
PZ...None.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Kennedy
MARINE...Kennedy
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Prepared by Boulder-Creek.com Weather at: Mon Oct 5 00:30:03 PDT 2026
From the National Weather Service
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