FXUS66 KMTR 312357
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
457 PM PDT Fri Jul 31 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1251 PM PDT Fri Jul 31 2026
- Gradual warming trend through the weekend 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
Saturday
- Strong and gusty winds develop over coastal waters north of
Point Reyes this weekend
&&
.SHORT TERM...
Issued at 1251 PM PDT Fri Jul 31 2026
(This evening through Saturday night)
Patches of stratus persist across the coast of the San Mateo
Peninsula and the Monterey Bay region, where an eddy over the bay is
keeping the stratus in place for a little while longer. Across the
region, skies are generally clear with smoke impacts from the
Woodside Fire observed across the Sonoma County valleys, and to a
lesser extent across the North Bay. A gradual warming trend
continues today as the high pressure system over the Desert
Southwest continues to impact our weather pattern. Highs today
range from the 90s in the inland valleys, up to 104 in the warmest
spots of southern Monterey and San Benito counties, to the middle
70s to lower 80s near the Bays, and the middle 60s along the
Pacific coast. Gusty onshore winds will develop this afternoon and
evening, with gusts reaching 25 to 35 mph along the coast,
through gaps and passes, within the Salinas Valley, and at the
ridgelines. High temperatures will be a couple degrees warmer on
Saturday, with triple digit highs possible in isolated locations
in the far interior North and East Bays, with winds ramping up in
the coastal waters as a passing trough tightens the pressure
gradient. With the stronger winds now coming into the domain of
more of the higher resolution modeling suites, the forecast is
calling for more widespread gale force gusts with isolated storm
force gusts possible in the northern outer waters.
Regarding the Woodside Fire, northwest winds will continue to impact
the wildfire site through the day with gusts of 25 to 30 mph
expected this afternoon and evening. Along the immediate coast,
temperatures will cool to the middle 50s with fair overnight
humidity recoveries. Poorer conditions are possible in the higher
elevations, where the thermal belts will result in poor humidity
recoveries and low temperatures in the middle 60s to lower 70s. In
terms of smoke impacts, high resolution HRRR model output depicts
smoke transport generally driven by northwest winds parallel to the
Sonoma County coast before the local wind pattern brings the smoke
through the Petaluma Gap into the North Bay valleys. For air quality
information, refer to products issued by the Northern Sonoma County
Air Pollution Control District within northern and western Sonoma
County, and the Bay Area Air Quality Management District in the rest
of the North Bay and SF Bay Area.
Patches of Moderate HeatRisk are expected to develop across the
interior today, 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. Considered
issuing a Heat Advisory for the weekend, but at this point there
hasn't been enough forecast coverage of the Moderate HeatRisk to
pull the trigger on issuing the Heat Advisory as of yet. 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.
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!
&&
.LONG TERM...
Issued at 1251 PM PDT Fri Jul 31 2026
(Sunday through next Thursday)
The heat continues into Sunday and Monday as the trough passes by
far to the north across western and central Canada, leaving the
ridging pattern generally intact through the early part of next
week. The current forecast shows a gradual cooling trend beginning
on Tuesday, but model ensemble cluster analysis generally agrees on
some form of ridging staying in place through the next week, with
the end result that temperatures are slow to drop and could remain
slightly above the seasonal average through the first week of
August.
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. 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.
&&
.AVIATION...
(00Z TAFS)
Issued at 431 PM PDT Fri Jul 31 2026
VFR conditions are expected to continue until after midnight with
the exception of KMRY and KHAF. Low confidence on MVFR/IFR
ceilings and timing for non-coastal sites during the overnight
hours. The marine layer will continue to be compressed with weak
organization indicated by the 00Z KOAK balloon.
Vicinity of SFO...MVFR ceilings are expected after midnight with
medium confidence in extent and timing. If MVFR/IFR ceilings
develop in the overnight hours, they are expected to lift by mid-
morning. Breezy to gusty onshore flow will persist through the
forecast period.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR is expected to persist through the
remainder of the afternoon evening with MVFR/IFR likely after
sunset and not until after midnight at KSNS. Breezy onshore winds
at times will persist through the forecast period.
&&
.MARINE...
(Tonight through next Wednesday)
Issued at 431 PM PDT Fri Jul 31 2026
Northwest winds increase to strong across the coastal waters with
some pockets of fresh breezes right along the coastline. Northern
coastal waters and the Big Sur coastal jet region will experience
north-northwest strong to near gale winds with frequent gale force
gusts through the weekend. In response to strengthening winds,
moderate seas build to very rough (13-15 ft) in the Northern zones
and rough (9-11 ft) in the Southern zones by Sunday and persist
into Monday. Thereafter, seas gradually subside back to moderate
(5-8 ft) by mid next week. Long period southerly swells persist
in our coastal waters through the weekend.
&&
.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 Saturday to 5 AM PDT Sunday for Pt Arena
to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory until 5 AM PDT Sunday for Pigeon Pt to Pt
Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt
to Pt Pinos 0-10 nm.
Small Craft Advisory from 9 AM Saturday to 5 AM PDT Sunday for
Pigeon Pt to Pt Pinos 0-10 nm.
Small Craft Advisory until 3 PM PDT Saturday for Pt Pinos to Pt
Piedras Blancas 0-10 nm.
Gale Warning from 3 PM to 9 PM PDT Saturday for Pt Pinos to Pt
Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...JM
MARINE...Navarrete
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Prepared by Boulder-Creek.com Weather at: Fri Jul 31 20:30:02 PDT 2026
From the National Weather Service
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