FXUS66 KMTR 010459
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
959 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

&&

.UPDATE...
Issued at 849 PM PDT Fri Jul 31 2026

It was another hot day cross the interior. In fact, far interior
locations over performed with the hottest locations ranging from
100-107 degrees. The 107 was at Pinnacles NP. Closer to the coast
and bays were warmer than Thursday, but still the marine layer
influence/onshore flow kept the real heat away. We've talked about
the temperature difference at the coast and inland the past few
days. We've also highlighted how sharp the temperature gradient
can been in just a matter of a few miles, thinking Monterey coast
to interior Monterey/Santa Lucia Range. Today let's highlight
temperatures in the vertical. Once again we'll head back to
Monterey county, more specifically the Big Sur coast. The marine
layer has been rather shallow the last few days, but still
ushering in that natural AC. Hwy 1 along the Big Sur coast had 
temps topped out in the 60s and 70s for the most part. Big Sur 
RAWS did hit 89, but that location is a little more protected. Now
if you head up the hill from Hwy 1, just 700-1000 feet temps
reached the low 90s. Anyone who hikes or trail runs in the Santa
Lucia range in July knows this happens a lot. Regardless, pretty 
impressive.

No evening update is expected. For those looking out the window
who live near the coast may see something they didn't last night,
clouds. The persistent NW flow and upwelling is more supportive 
of stratus tonight. Latest satellite imagery shows way more clouds
than last evening. Expect the coverage of clouds to fill in along
the coast. Two areas where clouds may not form due to weak 
offshore flow will be the Sonoma and Big Sur coasts.

&&

.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...
(06Z TAFS)
Issued at 947 PM PDT Fri Jul 31 2026

MVFR/IFR ceilings have moved in sooner than expected across the
the Bay Area and into the Salinas Valley, right on time at KMRY.
Timing and extent of the stratus and coverage is still low
confidence with the compressed marine layer measured at about 
500-600 ft from the KOAK 00z balloon. Coverage overall is greater 
than at this time 24hrs ago. Breezy onshore flow will persist 
overnight and become gusty Saturday afternoon.

Vicinity of SFO...As mentioned above, stratus has spilled over 
and moved through the San Bruno Gap into the Bay sooner than 
expected. Expect MVFR ceilings to drop into IFR with breezy 
onshore flow persisting. Expect ceilings to lift to VFR by late 
morning with diurnally driven gusty onshore flow through the 
remainder of the TAF period.

SFO Bridge Approach...Similar as SFO.

Monterey Bay Terminals...MVFR/IFR ceilings are expected to 
persist through late Saturday morning with a slight chance of LIFR
late in the overnight through sunrise. Expect breezy onshore flow
to persist, especially Saturday afternoon with MVFR/IFR ceilings 
likely returning before sunset.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 947 PM PDT Fri Jul 31 2026

Big Sur coastal waters have begun to see an increase in northwest
winds this evening, becoming strong, with the remaining outer
waters and coastal waters seeing increases through the remainder
of tonight and Saturday. Strong to near gale gusts will persist
through the weekend in both the outer and coastal waters, then to
the northern outer waters for the beginning of next week. The
strengthening winds will also build seas from rough to very
rough, especially the northern outer zones on Sunday into Monday
(13-15 ft). Seas will gradually subside back to moderate the first
half of next week. Long period southerly swell will continue
through the weekend as well.

&&

.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 9 PM PDT Sunday for Pt Arena 
     to Pt Reyes 0-10 nm.

     Small Craft Advisory until 5 AM PDT Sunday for Pt Reyes to 
     Pigeon Pt 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.

     Gale Warning from 9 AM Saturday to 3 AM PDT Monday for Pt Arena 
     to Pt Reyes 10-60 NM.

     Small Craft Advisory until 3 AM PDT Monday for Pigeon Pt to Pt 
     Pinos 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...JM
MARINE...JM

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Prepared by Boulder-Creek.com Weather at: Fri Jul 31 22:30:03 PDT 2026