National Weather Service United States Department of Commerce

Showers and Storms in the East; Dangerously Hot and Dry in the West

A frontal boundary will bring scattered showers and storms to portions of the Central and Eastern U.S. through the end of the week. Meanwhile, dangerous heat will intensify across the Intermountain West and expand into the Central U.S. by early next week. Elevated wildfire conditions will develop across portions of the Northern/Central Plains and air quality issues will persist in the Northwest. Read More >

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012
FXUS66 KMTR 060750
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1250 AM PDT Thu Aug 6 2026

...New SHORT TERM, LONG TERM, FIRE WEATHER...

.KEY MESSAGES...
Updated at 1248 AM PDT Thu Aug 6 2026

- Elevated fire weather conditions in the higher terrain Thursday

- Warming trend through Saturday will result in moderate to major
HeatRisk for the interior through Sunday

- Near-critical fire weather conditions in the higher terrain
Friday through Sunday

- Minor coastal flooding for bayshore locations along the San Francisco
Bay, San Pablo Bay, and Monterey Bay Saturday evening through
Thursday morning

&&

.SHORT TERM...
Issued at 1248 AM PDT Thu Aug 6 2026
(Today and tonight)

Longwave upper-level ridging will drift in from the Eastern Pacific
Ocean today, compressing the marine layer to near 1,500 feet in the
process. Temperatures will be near to slightly above normal with the
diurnal sea breeze. A surge of monsoonal moisture arrives today,
increasing surface dew points and relative humidity in the process.
Sensible weather wise, this will make it feel hotter and more
uncomfortable than what the thermometer reads. Areas of moderate
HeatRisk are expected in the interior with pockets of major in the
higher terrain of Monterey and San Benito Counties. Stagnant air
from the ridge may support haze from wildfire smoke. Elevated fire
weather conditions continue today above the marine layer.

&&

.LONG TERM...
Issued at 1248 AM PDT Thu Aug 6 2026
(Friday through Wednesday)

Surface high pressure over the Four Corners will build and expand
westward Friday and into the weekend. This will bring the hottest
conditions of the week and compress the marine layer further. Areas
of moderate HeatRisk across the interior on Friday will expand to
become widespread on Saturday with areas of major. To put this into
context: 850mb temperatures, 500mb heights, and PWAT values are all
forecast to exceed the 90th percentile Saturday. No records are
forecast with temperatures 10-15 degrees above normal for the
hottest spots. A potential wild card in the precision and subsequent
impacts of the forecast is the aforementioned surge of monsoonal
moisture. Mid-to-high level clouds would limit solar insolation
during the day and radiational cooling at night, potentially
resulting in cooler highs and warmer lows than the official
forecast. Even though the ridge will begin to break down and dry air
will begin to get filtered in from the northwest, cumulative impacts
from the heat and humidity will likely still be felt on Sunday. Near-
critical fire weather conditions are expected above the compressed
marine layer Friday through the weekend due to hot and dry
conditions with the diurnal sea breeze. Global ensemble clusters are
in agreement that upper-level shortwave troughing off the West Coast
will prevent the aforementioned ridge and subtropical high pressure
across the Eastern Pacific Ocean from joining forces and building
out of control across our area. Sensible weather wise, temperatures
will moderate to near normal with onshore flow Monday through
Wednesday. Minor coastal flooding is expected during the highest
high tide (evening/overnight) for bayshore locations along the San
Francisco Bay, San Pablo Bay, and Monterey Bay Saturday evening
through Thursday morning.

&&

.AVIATION...
(06Z TAFS)
Issued at 953 PM PDT Wed Aug 5 2026

VFR prevails early tonight with only KHAF and KSNS with MVFR
ceilings thus far. The stratus push inland isn`t as dramatic as
thought just three hours ago, but confidence remains high that it
will eventually spread over most of our area below 1500ft by sunrise
Thursday. With high pressure continuing to build, expect VFR
conditions by late morning for most terminals, possibly early
afternoon for the Monterey Bay sites as a compressed marine layer
retreats back to the coast.

Vicinity of SFO...Stratus lingering in vicinity of the terminals but
currently slow to make much more progress. The inland push isn`t
taking hold as quickly as though just a few hours ago, but
confidence is high that IFR/LIFR ceilings will develop after
midnight and persist through late morning. VFR through the
remainder of the forecast period once stratus retreats back to the
coast.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR ceilings will become IFR/LIFR after
midnight and continue through late morning at KSNS, possibly
early afternoon for KMRY. Moderate to high confidence that
IFR/LIFR ceilings return by early evening before sunset with VFR
most of the afternoon on Thursday.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 953 PM PDT Wed Aug 5 2026

Light to gentle breezes will continue through Thursday with seas
between 2-6ft. Northwest winds begin to increase Friday into the
weekend with building seas and hazardous conditions for small
craft. A long period southwesterly swell of 15-17sec begins on
Saturday, peaks on Sunday then begins to subside by the beginning
of next week.

&&

.FIRE WEATHER...
Issued at 1248 AM PDT Thu Aug 6 2026

Elevated fire weather conditions continue Thursday with hot and dry
conditions alongside the diurnal sea breeze. PSAs of Mid Coast to
Mendocino, Diablo/Santa Cruz Mountains, and Central Coast Interior
are all currently in the 97th percentile for ERC with Mid Coast to
Mendocino and Central Coast Interior forecast to reach daily record
values this weekend. This indicates potential for extreme burning
conditions. Even the more marine layer influenced PSAs of Bay Marine
and Central Coast are forecast to peak in the 80th-90th percentile.
Building high pressure will bring near-critical fire weather
conditions Friday through Sunday. Temperatures will be 10 to 15
degrees above normal with a shallow marine layer in place. Poor
minimum daytime relative humidity as low as 10% is expected in the
afternoons with little-to-no recovery expected overnight. The one
missing piece preventing this from being a Fire Weather Watch/Red
Flag Warning as of now is wind, it`s expected to be light. The
exception being through gaps/passes (namely Altamont Pass, the
Delta, and Pacheco Pass) and down the Salinas Valley. To add onto
this, the critical conditions are not expected to overlap spatially
(majority of a zone) or temporally (for at least 8 hours) to warrant
a product.

Sarment

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...JM
MARINE...JM

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