Technical NOAA Weather Discussion

FXUS66 KMTR 300455
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
955 PM PDT Wed Jul 29 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1153 AM PDT Wed Jul 29 2026

 - Breezy onshore winds expected each afternoon and evening
   through midweek

 - Gradual warming through Saturday, with Moderate HeatRisk for
   our interior locations

 - Elevated fire weather threat across the interior North and East
   Bay, Diablo and Santa Lucia Ranges this week

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

&&

.UPDATE...
Issued at 840 PM PDT Wed Jul 29 2026

Wednesday was almost a repeat of Tuesday with inland heat, cooler
temperatures at the coast, and onshore flow gusts of 25-40 mph.
One difference occurred over the last few hours as the sun began 
to set. The N-S pressure gradient between ACV and SFO increased to
nearly -5.5mb. Rule of thumb is anything approaching -6mb is 
pretty decent. As such, the pesky stratus that impacted portions 
of the coast for most of the day went poof. Last few images of the
visible satellite imagery shows a few clouds near Monterey 
Peninsula, but elsewhere is cloud free. The next logical question
is, do the marine layer clouds return tonight? Current forecast 
says yes, but the latest incoming model guidance says hold on. 00Z
HRRR and HREF are trending with less clouds returning overnight. 
Always hard to bet against stratus, but in this case the update 
overnight will likely trend less clouds by Thursday morning. 
Highest conf at this point returning stratus will be Monterey 
Bay/Salinas Valley/Big Sur Coast. 

Otherwise, no update needed.

MM

&&

.SHORT TERM...
Issued at 225 PM PDT Wed Jul 29 2026 (This afternoon through 
Thursday)

Water vapor imagery continues to show our deep trough over the
West Coast this afternoon, with predominately clear and sunny
skies prevailing across the state. Visible imagery does show the
marine layer lingering along a good portion of the coast,
including the San Francisco and San Mateo Coasts as well as the
Southern Monterey Bay. In fact, we are still trapped in the low
clouds down here, with Monterey only hitting 63 degrees so far. 
Inland areas though have warmed nicely though, with temperatures
within a degree or two of where they were at this time yesterday.
Gusts onshore winds will also prevail through this evening, before
gradually weakening overnight tonight. The marine layer will
return tonight, with low clouds filling in across the Bay Areas
later tonight and tomorrow morning. There are hints that it could
make it back into Napa again tonight, but confidence is not as
high as yesterday, given the ridge will start to build back into
the region on Thursday. Overnight temperatures will be similar to
what we saw last night, with most areas seeing temperatures in the
50s, and the coldest spots falling into the upper 40s. The warmer
and drier conditions in the thermal belts will also be quite 
pronounced again, with minimum temperatures struggling to fall 
below 70 degrees. 

High pressure will begin to back build into Central California on
Thursday, with dry and warmer conditions developing. Most areas
will see day time high temperatures increase 3 to 5 degrees on
Thursday. However, the marine layer will still help continue to
moderate temperatures along the immediate coast, so only expect a
degree or two of warming possible there.

&&

.LONG TERM...
Issued at 225 PM PDT Wed Jul 29 2026 (Thursday night through next
Tuesday)

Although this ridge of high pressure will strengthen over the
region on Friday and Saturday, the ensembles are suggesting that
it will flatten and retreat for Sunday, as the parent low finally
moves inland across the Pacific Northwest. As a result, expect
our warming trend to continue, especially for inland areas on
Friday and Saturday. A very shallow marine layer should remain
along the immediate coast these days, with weak onshore flow, 
helping to moderate temperatures there. As such, they may be 
slightly warmer, but the greatest warming will occur across the 
inland areas. At this point in time, the hottest locations look 
like they will warm to between 100 and 10, while the coast may 
only see temperatures in the upper 60s to low 70s.

As we move into Sunday, we would normally expect a cool down the
flattening of the ridge.  However, temperatures don't really 
appear to cool much if any across the inland areas on Sunday. 
Instead, it is more of a plateau, with conditions remaining hot 
across our inland areas. As this trough moves east on Sunday night
into Monday, some weak offshore could develop, especially for
North and East Bay on Sunday night and Monday. This means, we
could see even warmer conditions for Monday, and will need to
watch the extent of this offshore flow, because it could cause
even warmer temperatures in San Francisco for Monday than
currently advertised. 

High pressure then re-estabilishes itself for Monday through
Wednesday, with 850 mb temperatures climbing to between 27 and 28
deg C. This means inland areas could be down right hot, with the
hottest spots potentially as hot as 110. Winds look like they
should we weakly onshore for the coast, so believe these areas
will continue to be moderated. However, mid 70s may not be out of
the question. Palmer

&&

.AVIATION...
(06Z TAFS)
Issued at 955 PM PDT Wed Jul 29 2026

As noted above, the ACV-SFO pressure gradient was at -5.5mb which 
absolutely decimated the stratus along our coast. A few spots are 
holding on to it, but overall VFR conditions are prevailing. Near 
term hi-res models caught on to this pattern shift, which has made 
tonight's forecast tricky. The highest confidence for stratus is 
around Monterey Bay and the Salinas Valley, with low to medium 
confidence on what will happen at KHAF and the San Francisco Bay 
terminals. Trended the timing back for all sites, but that may need 
to be completely taken out if it doesn't materialize. If clouds do 
form, expect them to be short lived and erode by mid morning. 
Onshore winds return tomorrow, but may not be as breezy as the past 
two days. 

Vicinity of SFO...Low to medium confidence in the SFO forecast for 
tonight. Some models hint at stratus trying to make a return between 
9-11Z while other push it closer to daybreak, leading to only a few 
hours of reduced cigs. Was rather hesitant to completely pull 
stratus out of SFO so hinted at it with some SCT groups in a TEMPO, 
but that could easily be removed if we don't see much change in the 
ACV-SFO pressure gradient. Once we get past the cloud conundrum, we 
move on to breezy onshore winds returning Thursday afternoon and 
evening, which begin gradually decreasing after sunset. 

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Medium to high confidence in stratus 
returning around the terminals later tonight and into early Thursday 
morning. MVFR to IFR cigs are expected, with clearing occuring by 
mid morning and VFR conditions prevailing through the forecast 
period. Breezy onshore winds return for the afternoon and evening 
hours, but they do not appear to be as strong as Wednesday's
winds.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 955 PM PDT Wed Jul 29 2026

Fresh to strong northwest breezes with near gale force gusts
persist through the remainder of the week into the weekend.
Occasional gale force gusts with moderate seas are expected
through this evening and Thursday afternoon and evening along the
coastal jet regions south of Point Arena and south of Point Sur.
Additionally, gale force winds are continue to look favorable for
the northern waters this weekend, perhaps making into the western
most portions of the southern outer waters. Tropical activity
continues to produce long period swell across the coastal waters
into the weekend.

&&

.FIRE WEATHER...
Issued at 225 PM PDT Wed Jul 29 2026

The elevated fire weather threat will continue across portions of
the area through this weekend, and potentially into next week. 
Overnight RH recovery will remain 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 30 percent. This 
will be particularly true across the Mayacamas, highest peaks of 
the East Bay Hills, the Diablo Range, Santa Cruz Mountains, 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 will remain 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 
95th 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 225 PM PDT Wed Jul 29 2026

Long period southerly to southwesterly swell of 15-17 seconds 
will continue to impact our coastline over the next several days, 
bringing hazardous beach conditions to the Central Coast and the 
San Francisco Bay Area. Sneaker waves and strong rips currents 
will be the primary conditions, 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. Hazardous beach conditions are anticipated to persist 
through Saturday afternoon.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Saturday afternoon for CAZ006-
     505-509-529-530.

PZ...Small Craft Advisory from 2 PM to 9 PM PDT Thursday for Mry Bay-
     SF Bay N of Bay Bridge.

     Small Craft Advisory until 9 PM PDT Friday for Pigeon Pt to Pt 
     Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 9 PM PDT Thursday for Pt Reyes to 
     Pigeon Pt 0-10 nm.

     Small Craft Advisory until 9 AM PDT Saturday for Pigeon Pt to Pt 
     Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt 
     Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...Palmer
LONG TERM....Palmer
AVIATION...KR
MARINE...KR

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Prepared by Boulder-Creek.com Weather at: Wed Jul 29 22:30:02 PDT 2026
From the National Weather Service