FXUS66 KMTR 280726
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1226 AM PDT Tue Jul 28 2026

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

.KEY MESSAGES...
Updated at 1129 PM PDT Mon Jul 27 2026

- Breezy onshore winds expected each afternoon and evening through
  early midweek

- Gradual warming starting midweek, with Moderate HeatRisk for
  interior locations through the weekend

- 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 
  end of the week

&&

.SHORT TERM...
Issued at 1221 AM PDT Tue Jul 28 2026
(Today and tonight)


If you read the evening AFD update micro-climates were
highlighted. Seems fitting to kick off this AFD with another
micro-climate highlight. If one looks at the overnight satellite
imagery they'll notice only patchy stratus developing. I do 
expect more by morning, but patchy for now. So why is it patchy, 
pockets of offshore flow most notably over the N Bay and along the
Big Sur coast. Offshore flow is a drying and warming wind for our
region. Taking a closer look at Big Sur there are two sensors 
called Highlands Peak. It's close to midnight and both are 
reporting temperatures near 80 degrees. N to NE flow leads to 
compressional warming as the air descends the Santa Lucias, hence
the warm temperatures.

Tuesday will be another pleasant day weather wise most areas. The
longwave pattern continues to advertise broad upper level 
troughing just offshore and upper level ridging to the SE. 
Similar to Monday we'll see a large spread of temps from the 
coast to the interior. Onshore flow will keep coast/bays in check 
with highs in the 60s/70s. Farther inland with marine layer 
influence will see much warmer temperatures with highs in the 
upper 80s to near 100.

Given the temperature contrast expect another round of breezy
afternoon winds in the valleys and inland gaps/passes.

Tuesday night the upper level trough begins to ease with upper
level ridging building in from the east. As such, a more stable
marine layer will develop with slightly better stratus coverage.
Above the marine layer temperatures will be on the milder side.

&&

Issued at 1221 AM PDT Tue Jul 28 2026
(Wednesday through Monday)

Wednesday will be a transition day as the longwave pattern shifts
from nearby trough to a building ridge. It should be noted the
building ridge from the east brought very dangerous heat to the
Desert SW. Not expecting that here, but a marked warm up
nonetheless. Expect an initial jump in temps of 3-5 degrees from
Tuesday to Wednesday. Still seeing some night/morning marine
stratus given lingering onshore flow. Additionally, we will
continue to see the large temp spread from the coast to the
interior.  

Thursday through Monday - The heat dial gets turned up each day 
and peaks over the weekend before moderating early next week. The 
very warm upper level ridge to the east will overspread the region
for much of the long term. Projected 850mb temps will be in the 
mid to upper 20s, which when fully mixed will easily support temps
in the 105-110 range. However, onshore flow remains at the 
surface. Therefore, the fullest potential of the airmass will only
be realized across the interior. That's the key to keeping the 
coastal areas and bays in check temp-wise - onshore flow. Some 
guidance does show periods of easing onshore flow and that has 
bust potential written all over it with coastal areas ending up 
warmer than forecast. Confidence isn't high enough to fully buy 
that solution just yet. Much higher confidence exists for 
interior locations to experience triple digit heat. Given the 
very mild airmass thermal belts will be very active too with 
minor relief in the hills overnight. Could easily see temps 
staying in the upper 60s to mid 70s in the hills. Therefore, as 
daytime temperatures increase and less nighttime relief is 
observed overall HeatRisk increases. While most areas without any 
marine influence will be moderate HeatRisk from Thursday through 
early next week there will be pockets of Major to Extreme for 
interior Monterey/San Benito. As the weekend forecast becomes more
clear will need to take a look to see if a heat advisory is 
needed. 

Longer range guidance diverges on extent of the heat, but some
guidance keep the heat going for much of next week.  


&&

.AVIATION...
(06Z TAFS)
Issued at 1045 PM PDT Mon Jul 27 2026

Similar satellite trend as 24hrs ago with limited stratus impacting 
terminals with the exception of KHAF. Like the previous few nights, 
stratus is expected to push inland, though with a weaker SFO-SAC 
gradient as last night. Leaning closer towards pre-dawn hours for 
VFR/IFR ceilings to set in, with clearing times a little earlier 
than normal diurnal trends for this time of year, by mid-late 
morning Tuesday.

Vicinity of SFO...VFR through the remainder of this evening into 
the overnight hours. A steady fetch of onshore flow going into the
overnight is expected to produce MVFR ceilings as stratus 
eventually fills in through the San Bruno Gap and around the Bay 
Shore. The unorganized nature of the marine layer should allow for
clearing by late morning, with gusty onshore winds in the 
afternoon.

SFO Bridge Approach...Similar as SFO

Monterey Bay Terminals...VFR through the remainder of the evening
with MVFR/IFR ceilings expected after midnight with a slight 
chance of stratus filling in sooner than that. As is the case with
potentially filling in sooner than forecast tonight, there is a 
slight chance of ceilings lingering longer than mid-late morning 
Tuesday depending on whether a weak fetch of offshore flow just 
above the marine layer develops or not. 

&&

.MARINE...
(Tonight through next Sunday)
Issued at 1045 PM PDT Mon Jul 27 2026

Fresh to strong northwest breezes will persist through the week
into next weekend, especially across the outer waters. Coastal 
jet regions along Big Sur and Point Reyes may result in frequent 
gale force gusts. Moderate seas will become rough by the middle of
the week with the increasing northwest winds. Tropical storm 
activity will continue to produce long period southerly swells 
along our coastal waters into the weekend.

&&

.FIRE WEATHER...
Issued at 152 PM PDT Mon Jul 27 2026

The elevated fire weather threat will persist across portions of
the area through mid-week. Overnight RH recovery will remain
moderate at locations at or above 2,000 feet with values around 40
to 50 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 20 and 40 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 145 PM PDT Sun Jul 26 2026 

Distant tropical cyclones in the Eastern Pacific will continue to
generate 16-18 second (long-period) southwesterly swell which has
reached the coastline of the San Francisco Bay Area and Central 
Coast. As such, sneaker waves and strong rip currents are the 
primary concerns. Breaking waves can reach up to 12 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 Tuesday for Mry Bay-
     SF Bay N of Bay Bridge.

     Small Craft Advisory until 3 AM PDT Wednesday for Pt Arena to Pt 
     Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 PM PDT Thursday for Pigeon Pt to Pt 
     Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt 
     Reyes 10-60 NM.

     Gale Warning until 3 PM PDT Wednesday for Pt Pinos to Pt Piedras 
     Blancas 0-10 nm.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...JM
MARINE...JM

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Prepared by Boulder-Creek.com Weather at: Tue Jul 28 04:30:04 PDT 2026