Technical NOAA Weather Discussion

FXUS66 KMTR 011921
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1221 PM PDT Sat Aug 1 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 1220 PM PDT Sat Aug 1 2026

 - Moderate HeatRisk in the interior through Monday with some
   patches lingering through the next week

 - Near critical fire weather threat across the interior North and
   East Bays, and the Diablo and Santa Lucia ranges through Monday

 - Hazardous beach conditions across the Pacific Coast with an
   increased risk for sneaker waves and rip currents through the
   afternoon

 - Strong and gusty winds develop over coastal waters north of Pt
   Reyes through Sunday

&&

.SHORT TERM...
Issued at 1220 PM PDT Sat Aug 1 2026
(This evening through Sunday night)

The satellite picture reveals more extensive stratus coverage 
offshore compared to yesterday at this time, and patches of cloud 
persist across the coast of the Marin Headlands and the Monterey Bay 
region, where an eddy over the bay is keeping the stratus in place 
for a little while longer. The marine layer remains relatively 
compressed and stratus coverage will be rather limited tonight owing 
to a couple factors including an approaching weak cold front and 
possible bursts of offshore wind.

The weather pattern continues to be dominated by the high pressure 
system centered over the Desert Southwest and extending over the 
state, which is leading to widespread temperatures above the 
seasonal averages today. Highs today range from the upper 80s to 
middle 90s in the inland valleys today, with warm spots in the far 
interior North Bay, the eastern part of Contra Costa County, and 
southern Monterey and San Benito Counties seeing highs reaching the 
triple digits (up to 107 in southern Monterey County). Elsewhere, 
highs along the bays range from the middle 70s to the middle 80s, 
while the Pacific coast hovers in the middle 60s to lower 70s. On 
Sunday, morning lows range from the middle 50s to lower 60s in the 
lower elevations, to the middle 60s to the lower 70s in the higher 
elevations, and expect highs to be broadly similar to today's, 
possibly a couple degrees warmer in some spots.

A weak cold front currently off the coast of California, and
associated with an upper level trough over the Pacific Northwest
and British Columbia, will help tighten the north- south pressure
gradient as it comes into the northern Bay Area and the adjacent 
waters before dissipating, with the latest model projections 
putting tonight's peak SFO-ACV gradient in the -7 to -8 mb range.
A gradient this strong will help mix out the stratus and promote 
stronger winds in the coastal waters, with gale force gusts 
widespread and isolated storm force gusts possible. Fortunately 
these strong winds remain generally parallel to the coast, but a 
weak offshore push is possible tonight across the North Bay and 
Central Coast, which could cause warmer and drier conditions to 
extend all the way to the coast. Another stronger pulse of 
offshore wind is possible Sunday night into Monday morning. Not 
strong enough for a Wind Advisory, but strong enough to raise the 
fire weather concerns.

Widespread Moderate HeatRisk persists across the interior regions 
into Monday with patches of Moderate HeatRisk persisting into the 
rest of the 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. Some patches of Major HeatRisk, corresponding to a more 
widespread risk for heat-related illnesses, are also expected in the 
warmest parts of the interior Central Coast. 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. 
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 1220 PM PDT Sat Aug 1 2026
(Monday through next Friday)

The heat continues into Monday as the trough passes by far to the 
north across the northern Rockies and western and central Canada, 
leaving the ridging pattern generally intact through the early part 
of next week. Subtle cooling is possible in the wake of this trough 
passage Tuesday and Wednesday, with coverage of the Moderate 
HeatRisk becoming patcher in the inland SF Bay Area on those days. 
Breezy onshore winds are expected each afternoon and evening, and 
the longer range guidance shows temperatures rebounding for the 
latter part of the week as the ridge rebuilds over the region.

&&

.AVIATION...
(18Z TAFS)
Issued at 1155 AM PDT Sat Aug 1 2026

Stratus is making its way out of the remaining terminals, giving way 
for widespread VFR conditions to prevail through the day. Onshore 
winds increase through the afternoon and ease shortly after sunset. 
The marine layer remains compressed to around 1000 feet this TAF 
period, therefore low confidence on how expansive it will become 
overnight. High confidence for SJC and LVK to remain VFR. High 
confidence for coastal terminals to develop IFR ceilings after 
sunset as well. Elsewhere is kind of a toss-up with most model 
guidance (LAMP, HREF, REFS, & NBM) giving ~45-50% probabilities or 
less, with the NBM and LAMP being the most pessimistic. As a result, 
SCT007-010 decks were thrown in. If the stratus expands further 
inland, BKN-OVC ceilings are likely to develop around the specified 
times of the SCT cloud decks.

Vicinity of SFO...Moderate onshore breezes increase through the 
afternoon. Low chance for gusts in excess of 25 kt at SFO today, 
though sustained NW winds may increase to 15-18 kt and ease shortly 
after sunset. Low confidence on IFR ceilings at SFO and OAK tonight. 
Remained more optimistic this TAF period and hinted at the 
possibility for IFR rather than locking it in. If ceilings do 
develop they will likely develop later than last night around 10-12Z 
Sunday and scatter out by 16-18Z tomorrow.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Clear skies prevail this afternoon with a 
typical diurnal onshore breeze pattern. IFR ceilings will impact 
both terminals around 03-06Z, though medium confidence on the exact 
timing. Coastal drizzle/fog is possible overnight into early Sunday 
morning and ceilings may intermittently drop to LIFR (OVC003-004). 
The stratus is expected to scatter out by 18Z tomorrow. 

&&

.MARINE...
(Today through Thursday)
Issued at 1155 AM PDT Sat Aug 1 2026

Widespread north-northwest strong to near gale force breezes
continue through the weekend. Frequent gale force gusts persist
across the northern waters and the Big Sur coast with a
possibility  of occasional storm force gusts. Rough to very rough
wind driven  seas, around 10-15 feet, continue to build today into
tomorrow and  gradually subside early next week. Northern waters
will see the  higher end of wave heights and winds. Conditions are
expected to  decrease through the first half of next week. The
long period  southerly swell continues to weaken through the
weekend.

&&

.FIRE WEATHER...
Issued at 452 AM PDT Sat Aug 1 2026

Near critical fire weather conditions are expected through the
weekend and potentially into next week. Temperatures remain around
10 to 15 degrees above normal across the interior through early
next week with highs in the upper 80s to 90s. No major changes to
the forecasted dry conditions. Daytime humidity retention remains
poor across the interior (25-30%) with humidity values dropping 
into the 10s across the interior Central Coast, East Bay 
Hills/Valleys, and the higher elevations. Portions of the interior
Central Coast may see daytime humidity values drop into the single
digits this weekend into early next week. Overnight RH recovery 
remains poor at locations above 2,000 feet with values between 25 
to 40% expected with some favored locations struggling to reach 
even 25%. 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. Energy Release Components (ERC) 
are projected to climb above the 97th percentile across the 
interior Central Coast and Mid Coast to Mendocino (North Bay)
zone. ERC values are rapidly climbing across the Diablo-Santa 
Cruz zone (Diablo Mountains and Santa Cruz Mountains) with values
approaching the 97th percentile by next week. Diurnally breezy 
onshore winds are expected along the coast, mountain gaps and 
passes, and along the ridgelines each afternoon/evening. With 
near critically dry conditions and above normal temperatures 
expected, individuals across these areas 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 229 AM PDT Sat Aug 1 2026

Long period southerly to southwesterly swell continues through 
the afternoon, bringing hazardous beach conditions to the Central
Coast and the San Francisco Bay Area. Southerly swell will weaken
by late this afternoon with conditions to drop below Beach 
Hazards Statement criteria. Diminishing, low long period (1-2 ft 
at 13 to 14 seconds) southerly swell will continue into next week.
Sneaker waves and strong rip currents will be the primary threats
through the duration of the Beach Hazards Statement, 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 until 5 PM PDT this afternoon for CAZ006-
     505-509-529-530.

PZ...Gale Warning until 9 PM PDT Sunday for Pt Arena to Pt Reyes 0-10 
     nm.

     Small Craft Advisory until 5 AM PDT Sunday for Pigeon Pt to Pt 
     Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 PM PDT this afternoon for Pt Pinos 
     to Pt Piedras Blancas 0-10 nm.

     Gale Warning until 9 PM PDT this evening for Pt Pinos to Pt 
     Piedras Blancas 0-10 nm.

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

     Small Craft Advisory until 9 AM PDT Monday for Pigeon Pt to Pt 
     Pinos 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Navarrete
MARINE...Navarrete

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Prepared by Boulder-Creek.com Weather at: Sat Aug 1 16:30:03 PDT 2026
From the National Weather Service