Flash Flood Warning 3, NWS San Diego, CA

233 
WGUS76 KSGX 110018
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
518 PM PDT Mon Aug 10 2026

CAC065-110028-
/O.CAN.KSGX.FF.W.0003.000000T0000Z-260811T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
518 PM PDT Mon Aug 10 2026

...FLASH FLOOD WARNING IS CANCELLED FOR RIVERSIDE COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed any remaining road closures.

&&

LAT...LON 3357 11648 3356 11655 3356 11658 3361 11662
      3365 11664 3372 11651 3363 11644

$$

MM

Area Forecast Discussion
National Weather Service San Diego CA
1251 PM PDT Mon Aug 10 2026

.SYNOPSIS...
Minor to moderate HeatRisk today with cooler weather Tuesday and
beyond, high temperatures falling below normal by Wednesday.
Monsoon thunderstorm chances each day in the mountains through
Wednesday, with best chances and heaviest rain today and Tuesday.
Deepening marine layer through the end of the week with breezy
winds in the mountains and deserts.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

...UPDATED AVIATION DISCUSSION...

Mid level water vapor shows troughing to the northwest with the
ridge in place over the Four Corners region, poised to weaken into
Tuesday as the trough becomes more pronounced. Minor to moderate
HeatRisk continues today for much of the region, although
temperatures begin a cooling trend today, reaching near normal by
Tuesday afternoon. High clouds will continue to move into the region
today as southeasterly flow shunts moisture northward, but these
clouds shouldn't meaningfully limit storm potential in the mountains
this afternoon. The morning sounding indicated decent CAPE and
increasing PWs of 1.3-1.6", with models signaling a wide swath of
instability to set up today stretching from southwestern Arizona
into southeastern California. This instability, along with the ample
moisture in the mid and lower levels, will be key for more
widespread monsoonal thunderstorms today, likely kicking off as
early as noon. While much of the convection today will be
anchored to the mountains, a few storms may migrate into the
deserts and/or far eastern valleys with brief, heavy rainfall.
Rain rates in the higher terrain will be a bit more impressive
today, with 1"/hr or higher not out of the question for the San
Diego and Riverside county mountains. Further north in San
Bernardino, there will be a significant cut off of the moisture
near the border with LA County. Therefore, lesser max rain rates
closer to 0.5-0.75"/hr can be expected, with the strongest storms
likely on the eastern/northeastern slopes of the SB County
mountains. While widespread flooding isn't expected, some
localized spots, especially near the peaks or eastern sides of the
mountains, could see some brief flooding both today and tomorrow.
As always with any thunderstorm, frequent lightning, gusty winds,
and small hail will be possible. Ensure you are prepared to take
shelter in a sturdy and enclosed structure should you hear
thunder.

The ridge continues to weaken on Tuesday with some models now
indicating a weak easterly wave may move across Tuesday morning,
which could allow for some morning rainfall for the deserts and far
inland areas. Should this come to pass, a rumble of thunder or two
cannot be ruled out. This will be something to closely watch as any
morning convection could limit afternoon storms in the mountains. As
it stands now, additional moisture will be pushed into the region on
Tuesday with a slight decrease in the instability, allowing for
another round of monsoonal thunderstorms Tuesday afternoon.
Conditions look conducive for a rince-and-repeat of Monday, but with
the potential for slightly higher rain rates/localized flooding as
PWs peak above 1.5". Again, much of this will depend on what occurs
Tuesday morning with any easterly wave, but for now, will continue
to message widespread mountain thunderstorms for Tuesday afternoon.

After Tuesday, the aforementioned upper level trough will encompass
much of California as the state experiences a significant cooldown,
with temperatures falling to 3-10 degrees below normal Wed-Fri and
the marine layer deepens each day. This will be the first time in
nearly a month that highs will be below normal, so take advantage of
the cooler weather! Monsoonal moisture will linger in the region
which could allow for some abnormally warmer mornings, but with
limited forcing, afternoon thunderstorm chances will be falling
through the end of the week. Still, models continue to push for a
few storms over the San Bernardinos Wednesday afternoon as the
trough begins to move in. Otherwise, quieter weather for the end of
the week and weekend with cooler weather/a more robust marine layer
and afternoon breezy winds in the deserts and mountain passes.

&&

.AVIATION...
101945Z....Coast...VFR conditions expected this afternoon and
evening. Patchy low clouds to gradually develop overnight,
increasing in coverage and duration, with best chances of cigs
between 11-15Z Tuesday. Bases around 700-1000 feet MSL. Scatter out
of any cigs Tuesday by 17Z.

Valleys/Mountains/Deserts...SCT-BKN clouds mostly above 15000 feet
through 18Z Tue. Scattered TSRA over mtns with an isold TSRA or two
in the High Desert to 02z Tue with bases around 9000 feet MSL with
tops to 50000 feet. Any TSRA could produce lightning, strong
up/downdrafts and associated vis reductions.

&&

.MARINE...
No hazardous marine conditions are expected through Saturday.

&&

.BEACHES...
High tides will exceed 7 feet during evenings today through
Wednesday between 800-930 PM, resulting in minor tidal overflow of
low-lying areas along the beach. Surf will be low and is not
expected to add much to the flooding potential. Check the Coastal
Flood Advisory for details.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory from 6 PM this evening to 11 PM PDT
     Wednesday for Orange County Coastal Areas-San Diego County
     Coastal Areas.

PZ...None.

&&

PUBLIC...Zuber
AVIATION/MARINE/BEACHES...Small

Special Weather Statement
National Weather Service San Diego CA
1248 PM PDT Mon Aug 10 2026

CAZ050-058-062-102030-
San Diego County Mountains CA-San Diego County Deserts CA-
San Diego County Inland Valleys CA-
1248 PM PDT Mon Aug 10 2026

...A STRONG THUNDERSTORM WILL IMPACT EAST CENTRAL SAN DIEGO COUNTY
THROUGH 130 PM PDT...

At 1248 PM PDT, Doppler radar was tracking a strong thunderstorm over
Pine Valley, or near Mount Laguna, moving northwest at 10 mph.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Mount Laguna, Cuyamaca Rancho State Park, I-8 Between Pine Valley And
Boulevard, Pine Valley, Hwy S1 Between Lake Cuyamaca And Mount
Laguna, Descanso, Lake Cuyamaca, Guatay, Boulder Creek, and Captain
Grande Indian Reservation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3283 11635 3277 11649 3290 11668 3298 11662
      3299 11647
TIME...MOT...LOC 1948Z 149DEG 7KT 3285 11649

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Zuber

Special Weather Statement
National Weather Service San Diego CA
148 PM PDT Mon Aug 10 2026

CAZ055-060-102130-
Apple and Lucerne Valleys CA-San Bernardino County Mountains CA-
148 PM PDT Mon Aug 10 2026

...A STRONG THUNDERSTORM WILL IMPACT SAN BERNARDINO COUNTY THROUGH
230 PM PDT...

At 148 PM PDT, Doppler radar was tracking a strong thunderstorm near
Hwy 18 Between Baldwin Lake And Lucerne Valley, or 9 miles northeast
of Big Bear City, moving northwest at 10 mph.

HAZARD...Wind gusts up to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Eastern Lucerne Valley and northwestern Johnson Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3433 11665 3428 11677 3441 11683 3466 11684
      3473 11677 3465 11670
TIME...MOT...LOC 2048Z 145DEG 7KT 3437 11673

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

Zuber

Special Weather Statement
National Weather Service San Diego CA
209 PM PDT Mon Aug 10 2026

CAZ056-058-102200-
San Diego County Mountains CA-Riverside County Mountains CA-
209 PM PDT Mon Aug 10 2026

...A STRONG THUNDERSTORM WILL IMPACT RIVERSIDE AND NORTH CENTRAL SAN
DIEGO COUNTIES THROUGH 300 PM PDT...

At 209 PM PDT, Doppler radar was tracking a strong thunderstorm 7
miles northeast of Hwy 79 Between Warner Springs And Oak Grove, or 8
miles south of Anza. This thunderstorm was nearly stationary.

HAZARD...Wind gusts up to 50 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Anza, Warner Springs, Hwy 79 Between Warner Springs And Oak Grove,
Hwy 79 Between Santa Ysabel And Warner Springs, Aguanga, Cahuilla
Indian Reservation, and Los Coyotes Indian Reservation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3332 11652 3326 11668 3348 11681 3359 11677
      3356 11663
TIME...MOT...LOC 2109Z 158DEG 3KT 3344 11666

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH

Zuber