FXUS66 KMTR 310449
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
949 PM PDT Thu Jul 30 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1216 PM PDT Thu Jul 30 2026
- Gradual warming trend through Saturday with Moderate HeatRisk
in the interior through the early part of next week
- Elevated fire weather threat across the interior North and East
Bays, and the Diablo and Santa Lucia ranges through the early
part of next week
- Hazardous beach conditions across the Pacific Coast with an
increased risk for sneaker waves and rip currents through the
weekend
&&
.UPDATE...
Issued at 831 PM PDT Thu Jul 30 2026
First and foremost, let's discuss the weather impacting the
Woodside Fire on the Sonoma Coast. Weather wise, wind continues to
be the main driver of fire activity as temps are mild and
humidity is moderate. Winds this afternoon and this evening have
been very gusty and out of the northwest with peak wind gusts in
the 25-35 mph range. For the rest of the night winds will ease
slightly, but still be rather breezy out of the northwest.
Satellite imagery and stronger transport winds have definitely
shown widespread smoke coverage downstream of the fire in Petaluma
and Sonoma Valleys. As we see some cooling overnight expect the
smoke to settle into the valleys. For air quality impacts please
consult the Bay Area Air Quality Mng District. at baaqmd.gov
Quick update to the forecast was done this evening to include
smoke overnight and early tomorrow.
MM
&&
.SHORT TERM...
Issued at 1216 PM PDT Thu Jul 30 2026
(This evening through Friday night)
Generally clear skies prevail over the region with limited patches
of stratus lingering over the western side of San Francisco, along
the coast of the San Mateo Peninsula down to Pillar Point, and at
the immediate coast of the Monterey Bay region. Today will be the
first day of a warming trend that will dominate the weather pattern
for the next few days and bring temperatures above seasonal averages
to the inland regions, driven by a building high pressure system
expanding into California from the Desert Southwest. High
temperatures will range from the middle 80s to middle 90s across the
inland valleys, up to around 102 within the warmest spots of
southern Monterey and San Benito Counties, the lower 70s to lower
80s along the Bays, and the lower to middle 60s along the Pacific
coast. An onshore push will develop this afternoon and evening,
bringing gusts of 25 to 35 mph along the coast, through gaps and
passes, and within the Salinas Valley.
Tonight, expect the building high pressure system to compress the
marine layer, limiting any stratus and fog impacts to the immediate
coastal regions. Low temperatures on Friday morning range from the
middle to upper 50s in the valleys, to the 60s and lower 70s within
the thermal belts. Highs on Friday will continue to warm with
temperatures around a couple degrees warmer than today's across most
of the region, save the immediate coast where the compressed marine
layer keeps the region cooler.
Patches of Moderate HeatRisk develop in the interior on Friday,
followed by more widespread Moderate HeatRisk in the interior
Saturday through the early part of next week. This corresponds to a
moderate risk for heat related illnesses for sensitive populations,
including children, the elderly, pregnant women, people with certain
medical conditions, and people who work or live outdoors without
adequate shelter or hydration. Follow these tips to avoid heat-
related illnesses:
* 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 1216 PM PDT Thu Jul 30 2026
(Saturday through next Wednesday)
Saturday looks to be the warmest day of this strand of warming with
triple digit highs possible in the far interior regions of northern
Sonoma, northeastern Napa, and eastern Contra Costa counties, while
southern Monterey County sees highs reaching 105 with some isolated
and heavily favored locations making a run for 110. Elsewhere the
inland valleys remain in the 90s while downtown San Francisco and
Oakland hover in the middle 70s to lower 80s. On Sunday, a trough
passing by the Pacific Northwest will interrupt the building ridge
and cause temperatures to plateau, but large scale ridging returns
the next day and could continue into the middle of the next week.
Regarding potential strong winds across the coastal waters this
weekend, the ECMWF EFI backed down a little bit from what the
previous forecaster was seeing last night, but are still showing
high EFI values with a strong shift of tails. Or in layman's terms,
there's a strong signal for strong winds and a relatively high
probability for remarkably strong winds, a "boom" situation, if you
will. The PG&E WRF model continues to show a swath of storm force
gusts over 60 mph across the northern waters off the coast of Sonoma
and Marin counties, but it's almost alone in depicting this, with
the deterministic GFS and the experimental RRFS showing isolated
storm force gusts in the area while the NAM12 and deterministic
ECMWF keep wind gusts at gale force. Will be interesting how the
other high resolution models, namely the higher-resolution NAM and
the HRRR, depict the wind gusts in this are where the time comes.
For now, there wasn't enough confidence to bump up the wind gusts
for the weekend.
In addition, the upper level pattern could bring us a couple of
offshore bursts over the region, with a notable pulse Sunday night
into Monday particularly across the North Bay and SF Bay regions. As
noted by the previous forecaster, the fire weather concerns
regarding nocturnal drying and downslope warming are obvious, but
that downslope warming could also cause coastal temperatures to be
much warmer than the forecast if it extends through Monday.
As a final note, beach hazards and fire weather concerns continue
into the weekend. See the BEACHES and FIRE WEATHER sections for more
details. One less spark, one less fire, and never turn your back to
the ocean!
&&
.AVIATION...
(06Z TAFS)
Issued at 948 PM PDT Thu Jul 30 2026
Satellite this evening shows a few blips of stratus in San Mateo and
Monterey counties, otherwise clear skies exist elsewhere. Smoke from
the Woodside Fire has billowed south and eastward, which has brought
reduced cig and vis to KSTS this evening. The HRRR smoke model
indicates there may be less smoke produced overnight, but given that
it has already sunk into the valleys of the North Bay, we could
continue to see periods of MVFR to IFR visibility and ceiling when
winds ease. Otherwise, when sites are not being influenced by
wildfire smoke, look VFR conditions are expected to prevail tonight
and into tomorrow. The marine layer is expected to be around 500-
800ft which will keep stratus development limited. The areas that
have the best chance for stratus tonight are around Monterey Bay and
Half Moon Bay. Some models hint at it building back into the Napa
Valley region and around Oakland, but confidence is low and opted to
continue the hint of stratus at these sites. Medium to high
confidence in the forecast.
Vicinity of SFO...Onshore winds continue to gradually decrease this
evening, falling to less than 10kt overnight. The tougher question
is in regard to the stratus forecast. As mentioned above, the marine
layer is expected to be around 500-800ft with the KOAK sounding
showing a fairly dry profile. Current thinking is KFSO will likely
stay VFR through the period and if any low clouds try to form it'd
likely be between 10-14Z. Outside of that look for breezy onshore
winds to return Friday afternoon and evening, sustained speeds will
be around 15kt with gusts up to 20-23kt possible. Medium to high
confidence in the forecast.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...The most likely area to see stratus late
tonight and into Friday morning is the Monterey Bay and northern
Salinas Valley. Opted to IFR cigs tonight, and hinted at LIFR cigs
with FEW004. If we get LIFR cigs they'd likely occur around or
shortly after sunrise. Skies clear by mid morning, with VFR
conditions prevailing afterwards. Models show stratus attempting to
come in around the end of the TAF cycle, but confidence was too low
to add anything other than FEW007. Medium to high confidence in the
forecast.
&&
.MARINE...
(Tonight through next Wednesday)
Issued at 948 PM PDT Thu Jul 30 2026
Fresh northwest breezes become strong across our coastal waters
by Saturday with moderate seas building to rough in response.
Conditions will become dangerous, late Saturday and into Sunday,
especially across the northern waters. Northerly winds continue
to increase on Sunday with severe gale to storm force gusts north
of Point Reyes and gale force gusts from Point Reyes to Pigeon
Point. Seas will to become very rough. Winds gradually decrease
for the early portion of next week, which will allow very rough
seas to subside to moderate by Wednesday. A long period southerly
swell continues to impact our coastal waters from distant
tropical activity.
&&
.FIRE WEATHER...
Issued at 1216 PM PDT Thu Jul 30 2026
The overall fire weather picture remains similar to the previous
discussion, with elevated fire weather threats persisting at the
higher elevations through the weekend and possibly beyond.
Overnight RH recovery remains moderate to poor at locations at or
above 2,000 feet with values between 35 to 45 percent, with some
favored locations struggling to even reach 25 percent. This will
be particularly true across the Mayacamas, highest peaks of the
East Bay Hills, the Diablo Range, the Santa Cruz Mountains, the
Santa Lucia and Gabilan Ranges. Nocturnal drying (rapid decrease
in RH through the pre- dawn hours) may also transpire which will
increase the burn period or time in which fire behavior may remain
active. Afternoon RH remains critically dry with values between
15 and 30 percent, with far southern portions of the interior
Central Coast potentially seeing min RH near 10 percent. Energy
Release Components (ERC) are projected to climb above the 97th
percentile across the interior Central Coast. Individuals across
the area are advised to avoid activities that may spark a fire.
Fire crews are urged to exercise extra caution when executing any
prescribed burns, especially where fuels, topography, and weather
align.
&&
.BEACHES...
Issued at 1216 PM PDT Thu Jul 30 2026
Long period southerly to southwesterly swell of 14-17 seconds
continues to impact our coastline through at least Saturday
afternoon, bringing hazardous beach conditions to the Central
Coast and the San Francisco Bay Area. Sneaker waves and strong rip
currents will be the primary threats, with breaking waves up to
10 feet along some south and southwest facing beaches and break
points, such as Santa Cruz, Pacifica, and parts of Stinson or
Ocean Beach. This can be particularly surprising when wave heights
increase suddenly after a period of seemingly tranquil wave
action. In fact, sneaker waves can have 20+ minutes in between the
larger sets (breaking waves) with significant "flat/calm looking"
times between them. Due to the long period, sneaker waves are
powerful and can catch beachgoers by surprise, resulting in people
and pets being swept into the cold, turbulent ocean. Rip currents
are strong enough to pull even the strongest swimmers away from
shore. Check marine conditions before you head out! Swim near a
lifeguard, if possible. Maintain a safe distance from the water,
and stay away from jetties, piers, beachside rocks, and other
waterside infrastructure. Never turn your back to the ocean and if
you have small children or pets at the beach, please keep an eye
on them.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Saturday afternoon for CAZ006-
505-509-529-530.
PZ...Small Craft Advisory until 9 AM PDT Saturday for Pt Arena to Pt
Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
Gale Warning from 9 AM to 3 PM PDT Saturday for Pt Arena to Pt
Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory from 3 PM Friday to 3 PM PDT Saturday for
Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 PM PDT Friday for Pigeon Pt to Pt
Pinos 0-10 nm.
Small Craft Advisory from 9 AM to 3 PM PDT Saturday for Pigeon
Pt to Pt Pinos 0-10 nm.
Small Craft Advisory until 3 PM PDT Saturday for Pigeon Pt to Pt
Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...KR
MARINE...KR
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Prepared by Boulder-Creek.com Weather at: Thu Jul 30 22:30:04 PDT 2026
From the National Weather Service
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