FXUS66 KMTR 051747
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1047 AM PDT Mon Oct 5 2026
...New AVIATION...
.KEY MESSAGES...
Updated at 1213 PM PDT Sun Oct 4 2026
- Hazardous heat conditions persist inland, never leave children
or pets in unattended vehicles!
- Elevated fire weather conditions continue across the interior
through Thursday
- Temperatures cool closer to normal for the end of the week
into next weekend
&&
.UPDATE...
Issued at 930 AM PDT Mon Oct 5 2026
With increasing confidence in heat impacts continuing through
Thursday, the Heat Advisory has been extended through 10 PM
Thursday for the inland regions of the Bay Area and Central Coast.
Despite a couple degrees of cooling from Wednesday's highs, the
cumulative heat impacts will continue and a moderate risk of heat-
related illnesses continues into Thursday.
DialH
&&
.SHORT TERM...
Issued at 1230 AM PDT Mon Oct 5 2026
(Today and tonight)
The weak upper level disturbance embedded in the broader scale
ridging can be seen on satellite shifting inland overnight.
Unfortunately it offers no relief in cooling temperatures and will
reinforce offshore flow as it continues to exit east during the day
today. A Heat Advisory remains in effect for most of our area
through Wednesday night, however the advisory for the immediate
coastline from Sonoma County south to Santa Cruz County was allowed
to expire on schedule. Todays high temperatures will continue to run
15-25 degrees above normal with overnight lows generally running 10-
20 degrees above normal, offering little to no night time relief to
the moderate to major HeatRisk we'll see through Wednesday across
the interior. Despite a return of stratus along the coastline,
expect the marine layer to continue to hold primarily to the coast
today while remaining compressed and fighting fetches of offshore
flow.
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 1230 AM PDT Mon Oct 5 2026
(Tuesday through Sunday)
The synoptic scale ridging across our region will be reinforced
through mid-week in the wake of the weak upper level system to our
north exiting east today. Temperatures today through Wednesday will
be very similar with little day to day variability for most
locations. Another weak upper level system develops offshore for the
middle to end of the upcoming work week, and will combine with a
more potent disturbance embedded in the polar jet to begin to lower
H50 heights by Thursday with a return to more normal temperatures
for the end of the week into the weekend, when daytime highs are
expected to fall back to or below normal by the weekend.
&&
.AVIATION...
(18Z TAFS)
Issued at 1047 AM PDT Mon Oct 5 2026
A shallow marine layer (around 500 feet in depth) has returned
allowing for coastal stratus and fog to return to the coastal
sites. As surface temperatures warm, expecting mostly VFR
conditions to persist through the early evening before a return of
stratus and/or fog returns to coastal sites late this evening and
into Tuesday morning. The greatest potential for sub-IFR will be
at HAF, MRY, and SNS with the rest of the region remaining VFR
throughout the TAF period. Onshore winds will increase today and
be slightly stronger than previous days before easing after sunset
and more so into Tuesday morning. Any low ceilings and/or fog are
likely to dissipate between 16Z-17Z Tuesday.
Vicinity of SFO...VFR. Onshore winds will increase by late
morning and persist into early evening before diminishing. West to
northwest winds will be strongest this afternoon through mid-
evening with winds forecast to be up to 16kt. While there is a low
probability (generally 20-25%) of sub-MVFR from 12Z-17Z Tuesday,
have these out of the forecast at this time.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR. Onshore winds will increase this
afternoon before diminishing after sunset. Sub-IFR conditions are
forecast to return to the region late this evening and persist
into Tuesday morning with generally moderate to high confidence of
occurrence. Low ceiling and fog will begin to dissipate between
16Z- 17Z Tuesday with afternoon heating.
&&
.MARINE...
(Today through Saturday)
Issued at 930 AM PDT Mon Oct 5 2026
An extensive low stratus and fog layer is steadily advancing
eastward across the coastal waters and will reach much of the
coastline throughout the morning and into the afternoon. 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 306 AM PDT Mon Oct 5 2026
Strong ridging aloft will lead to hot and dry conditions through
Thursday with elevated fire weather conditions across the higher
elevations. Poor to very poor overnight humidity recoveries will
continue across the thermal belts with pushes of offshore flow
each morning. Hazardous heat will continue through Thursday with
major to extreme risks of heat-related illnesses across most
mountain ranges. A pattern change later this week will bring
cooler conditions to the region.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 10 PM PDT Thursday for CAZ503-504-506-508-
510-512>518.
PZ...None.
&&
$$
SHORT TERM...JM
LONG TERM....JM
AVIATION...RGass
MARINE...RGass
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Prepared by Boulder-Creek.com Weather at: Mon Oct 5 12:30:04 PDT 2026
From the National Weather Service
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