FXUS66 KMTR 111146
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
439 AM PDT Thu Jun 11 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1202 AM PDT Thu Jun 11 2026
- Hot and dry through Saturday with a moderate risk of heat-
related illnesses for interior locations today and Friday
- Critical fire weather threat for the interior North Bay and the
East Bay Mountains through the morning with critically dry
conditions persisting into the afternoon
- Increased risk of sneaker waves and strong rip currents along
south and southwest facing beaches through the weekend
- Minor coastal flooding due to higher than normal high tides
anticipated across coastal regions of the San Francisco Bay
Area
&&
.SHORT TERM...
Issued at 1202 AM PDT Thu Jun 11 2026
(Today and tonight)
It is going to be a hot day today, the hottest of the week, but the
more interesting setup in the short term is taking place through the
overnight period as the fire weather concerns increase The latest
surface analysis shows that pressures are beginning to rise over the
Great Basin, allowing the low level pressure gradients to increase
between the Great Basin high and the thermal trough over the state.
A burst of offshore winds sets up through the night over the
interior mountains of the North and East Bays as a low level jet
comes into the region from the Sacramento Valley. Gusts of 30 to 40
mph are expected across the higher elevations, with the potential
for mountain wave activity downwind of the higher terrain features
resulting in the possibility that gusts exceed 60 mph in these
areas. As for elsewhere in the region, the low level jet loses its
strong winds before making it to the South Bay and Central Coast,
and within the valleys, the decoupling boundary layer will shield
lower elevation locations from the strong winds.
In addition to the strong gusts, the offshore winds will result in
poor overnight humidity recoveries, and as a result, Red Flag
Warnings are in effect through 9 AM this morning across the interior
mountains of the North and East Bays. People in the area should obey
any fire restrictions/burn bans, extinguish any camp fires, secure
tow chains trailers/RVs, and NEVER toss cigarette butts out the
window. Remember, one less spark, one less wildfire. The winds will
abate during the day, and will remain below critical fire weather
thresholds, but people should still be vigilant as humidities remain
very dry.
As for temperatures, morning lows will range from the middle 50s to
middle 60s in the lower elevations, up to the upper 60s to middle
70s within the thermal belts. Today's highs will be the warmest of
the week, with highs ranging from the 90s to the triple digits in
the inland valleys, up to 104 in the warmest locations, while the
Bays see highs in the 80s and lower 90s and the Pacific coast, the
middle 60s to middle 70s. One thing to keep an eye on is the
potential shown by some of the higher resolution models that a
southerly surge to develop, and potentially reach as far north as
the Monterey Bay region by the afternoon hours, which would
definitely impact the temperatures forecasts for the immediate
coastal areas. A Heat Advisory will come into effect today for the
East Bay, South Bay, most of the North Bay, and the eastern side of
San Mateo County, as Moderate HeatRisk develops in the area,
corresponding to a risk for heat-related illnesses amongst sensitive
populations, including children, the elderly, pregnant women, people
with chronic conditions, and people who work or live outdoors
without adequate shelter or hydration. Follow these tips:
* 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.
High astronomical tides combined with swell and thermal-driven surge
will result in minor coastal flooding around high tide across low-
lying areas near the Bayshore this evening. Coastal Flood Advisories
are in place for the entire Bayshore this evening, as up to 1.2 feet
of inundation is expected around high tide, which for the San
Francisco tidal gauge is at 851 PM tonight. Finally, those people
planning to go to the beach should be on the look out for sneaker
waves and strong rip currents. More information is available in the
BEACHES section.
Tonight into Friday morning, low temperatures might dip a little bit
within the thermal belts, and the offshore winds will be much less
strong compared to what we'll see tonight. If a southerly surge
does develop, it will continue to spread further up the coast
overnight.
&&
.LONG TERM...
Issued at 1202 AM PDT Thu Jun 11 2026
(Friday through Wednesday)
Rather unusual uncertainty continues for the high temperature
forecast on Friday. As the previous forecaster noted, with the upper
level trough moving to the east, the low level pressure gradient
should ease and a diffuse trough coming from the north will attempt
to encourage onshore flow. To this, add the potential for the
aforementioned southerly surge to potentially re-establish a marine
layer right at the immediate coast. All said, I am generally in
agreement with the previous forecaster that a more structured sea
breeze will develop on Friday and potentially a weak cold front
comes through the North Bay. The Heat Advisory continues for the
interior East and South Bays, where there is higher confidence for
the Moderate HeatRisk to continue, and I can't rule out extensions
of heat-related messaging into the weekend. This weekend will also
see the ridge extending north into the Pacific Northwest and British
Columbia, and some shortwave ridging possible over California, which
could bring us a couple of bursts of offshore flow. Ensemble model
cluster analysis converges on the ridge beginning to flatten early
next week, and hints at the potential for more zonal flow or
troughing towards the latter part of next week.
With high confidence in high astronomical tides into the middle of
next week, the Coastal Flood Advisory has been extended into the
early morning of Wednesday next week, and depending on the observed
surge, some minor flooding may be observed along the Pacific coast
over the next few days. Long period swells will also move through
the waters over the weekend, leading to an increased risk for
sneaker waves and rip currents.
&&
.AVIATION...
(12Z TAFS)
Issued at 439 AM PDT Thu Jun 11 2026
A strong high pressure system continues over the area. The ACV-SFO
pressure gradient is strong at 8.8 mb (though it's beginning to ease
somewhat), WMC-SFO is 8.9 mb and RDD-SAC is 4.5 mb supporting
downsloping, offshore winds. SFO-SAC is weak onshore 1.2 mb
indicating a surface trough is located in the CA interior. To the
south near Point Conception satellite shows stratus is gathering and
moving northward.
It's a high confidence VFR forecast today with exception of a few
patches of morning low stratus/fog /LIFR-IFR/ along the immediate
coastline. Northerly winds are gusty aloft; low level wind shear
remains in the 12z TAFs for the morning hours until at least the
RDD-SAC pressure gradient and winds have a chance to subside.
On the larger scale the strong high pressure system will gradually
shift northward allowing a shallow, coastally trapped southerly
wind reversal to continue making a run up along our coastline
today. High resolution model output shows stratus /IFR/ reaching
the Monterey Bay by afternoon and KHAF Airport by early evening.
KMRY will likely develop a southwesterly wind in the afternoon,
stratus /IFR/ is forecast by 05z in the evening. KSNS often sees
the stratus first before KMRY does in this pattern. It's a
challenging, potentially quickly evolving pattern with potential
impacts to aviation in the near term. There are one or two pushes
left to the NW winds over the coastal waters that'll be juxtaposed
to developing SE winds moving up along the coastline, this pattern
may develop fairly quickly. Sea surface temperatures have undergone
a fair amount of cold water upwelling and the return of stratus
clouds may quickly become a blanket over recent cooling e.g.
protecting sea surface temps from solar input. High resolution
model forecasts show stratus and fog /LIFR-IFR/ moving farther
northward tonight and Friday morning. Partial stratus and fog
/LIFR-IFR/ intrusion into the Bay Area is likely Friday morning.
Vicinity of SFO...VFR. Low level wind shear until 16z today. West
to northwest wind 5 knots becoming variable to possibly northeast
5 knots during the morning. Lower confidence regarding the afternoon
wind, much depends on how well the coastally trapped southerly wind
reversal develops. For now a wind shift to westerly is indicated
for the afternoon post 21z today.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR except a patch or two of stratus/fog
/LIFR-IFR/ this morning. 12z KMRY and KSNS TAFs lean toward the
development of a southerly wind reversal arriving by afternoon.
Stratus /IFR/ arrives this evening with a southerly wind reversal.
IFR stratus prevailing tonight and Friday morning. Light and
variable winds becoming southwesterly at KMRY and northwesterly
at KSNS in the afternoon.
&&
.MARINE...
(Today through Tuesday)
Issued at 349 AM PDT Thu Jun 11 2026
Gale force gusts linger in the norther outer waters while winds
overall will weaken to moderate to gentle breezes through the
weekend and early next week. Rough seas will steadily diminish
through early next week as the winds ease.
&&
.FIRE WEATHER...
Issued at 1202 AM PDT Thu Jun 11 2026
A quick update to say that gusty winds are beginning to develop
across the North Bay interior mountains, with the strongest gusts
reported at the PG&E station Mount St. Helena West at 66 mph, while
many stations in the North and East Bay interior mountains
continuing to report relative humidities in the 20s. The Red Flag
warning for these areas continues through 9 AM with poor overnight
humidity recoveries and strong gusts contributing to critical fire
weather conditions, while elevated fire weather threats continue
tonight over the eastern Santa Clara hills.
From the previous forecaster: Increasing northerly 20 foot winds of
10 to 20 mph with gusts to 45 mph are forecast late tonight into
Thursday morning. With energy release components trending above the
85th percentile and overnight humidity recovery anticipated to be
below 40 percent, a critical fire weather threat is expected to
unfold. The threat will be greatest across the North Bay Interior
Mountains and East Bay Hills. Pending ignitions, extreme fire
behavior and/or spread is likely during the overnight hours into
Thursday morning. Winds will subside after 9am Thursday, however,
afternoon humidity values in the teens to near single digits are
forecast across interior regions. Minimal shading will help to cure
fuels further in the afternoon and while wind speeds are largely
anticipated to fall below 10 mph, fire spread will remain a
possibility, particularly in areas with the favorable alignment of
weather, fuels, and topography.
&&
.BEACHES...
Issued at 100 PM PDT Wed Jun 10 2026
Long period swell will continue, likely during the weekend,
especially for south and southwest facing beaches. Hazardous beach
conditions are advertised, specifically for moderate to steeply
sloped beaches along the Pacific Coast of the North Bay, San
Mateo, Santa Cruz counties. Be sure check beach conditions before
you head out. Sneaker waves will run up the beach much farther
than other waves, potentially catching beachgoers by surprise and
resulting in people being swept into the water. Rip currents are
strong enough to pull the strongest swimmers away from shore. Swim
near a lifeguard if possible. Stay back from the beach, and away
from jetties, piers, beachside rocks, and other infrastructure
near the water. Never turn your back to the ocean!
&&
.CLIMATE...
Issued at 1235 AM PDT Wed Jun 10 2026
The following are the record highs for June 11th.
Station Record Highs June 11th
Santa Rosa 100 in 2019
San Rafael 97 in 1985
Napa 102 in 2019
Livermore 105 in 1985
San Francisco 92 in 2019, 1877
SFO Airport 98 in 2019
Redwood City 102 in 2019
Oakland Museum 99 in 2019
Half Moon Bay 85 in 2019
San Jose 99 in 2019
Monterey Airport 92 in 2019
Salinas Airport 104 in 2019
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory from 7 PM this evening to 3 AM PDT
Wednesday for CAZ006-508.
Heat Advisory from noon today to 11 PM PDT this evening for
CAZ503-504-506-508.
Red Flag Warning until 9 AM PDT this morning for CAZ504-515.
Beach Hazards Statement through this evening for CAZ505-509-529.
Coastal Flood Advisory until 3 AM PDT Wednesday for CAZ506.
Heat Advisory from noon today to 7 PM PDT Friday for CAZ510-
513>515.
PZ...Gale Warning until 3 AM PDT Friday for Pt Arena to Pt Reyes 10-
60 NM.
Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt
to Pt Pinos 10-60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Canepa
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Prepared by Boulder-Creek.com Weather at: Thu Jun 11 06:30:03 PDT 2026
From the National Weather Service
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