Extreme Heat Warning
URGENT - WEATHER MESSAGE
National Weather Service Flagstaff AZ
140 PM MST Tue Aug 18 2026
AZZ006-210300-
/O.CON.KFGZ.XH.W.0013.000000T0000Z-260821T0300Z/
Grand Canyon Country-
Including the cities of Tusayan, Grand Canyon Village, Grand Canyon
North Rim, and Supai
140 PM MST Tue Aug 18 2026
...EXTREME HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM MST THURSDAY
BELOW 4000 FEET...
* WHAT...Dangerously hot conditions expected below 4000 feet, with
daytime temperatures ranging from 96 to 102 degrees at Havasupai
Gardens, and 107 to 111 degrees at Phantom Ranch.
* WHERE...Lower elevations of the Grand Canyon.
* WHEN...Until 8 PM MST Thursday.
* IMPACTS...Most individuals will be at risk for heat-related
illnesses without effective cooling or adequate hydration,
especially with prolonged outdoor exposure.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
This warning is reserved for only the hottest days of the year and is
issued when temperatures are expected to rise to dangerous levels.
Day hikers on Bright Angel Trail should descend no farther than 1 1/2
miles from the upper trailhead. Between the hours of 10 AM and 4 PM,
hikers should be out of the canyon or at Havasupai Gardens or Bright
Angel campgrounds, physical activity is discouraged. All hikers
should have adequate gear, including a wide-brimmed hat, sunscreen,
salty snacks, sufficient water, and electrolyte mix. Doubling your
calorie intake helps maintain your energy.
Hike smart.
&&
$$
McCollum
URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
1147 AM MST Tue Aug 18 2026
AZZ530>533-535-536-CAZ562-565>567-569-570-191000-
/O.CON.KPSR.XH.W.0008.000000T0000Z-260822T0300Z/
Parker Valley-Kofa-Yuma-Central La Paz-Southeast Yuma County-Gila
River Valley-Imperial County Southwest-Imperial County Southeast-
Imperial County West-Imperial Valley-Palo Verde Valley-Chuckwalla
Valley-
Including the cities of Ocotillo, Quartzsite, Martinez Lake,
Winterhaven, Vicksburg Junction, Harcuvar, Alamorio, Coolidge
Springs, Vicksburg, Blythe, Midland, Mountain Spring, Salome, Fortuna
Foothills, Salton City, Coyote Wells, Calexico, Winona, El Centro,
Brawley, Brenda, Palo Verde, Ripley, Palm Canyon, Plaster City, Yuma,
Ehrenberg, Parker, and Ligurta
1147 AM MST Tue Aug 18 2026 /1147 AM PDT Tue Aug 18 2026/
...EXTREME HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM MST /8 PM PDT/
FRIDAY...
* WHAT...Dangerously hot and humid conditions. Afternoon temperatures
106 to 114 expected. Major Heat Risk.
* WHERE...Portions of southwest Arizona and southeast California.
* WHEN...Until 8 PM MST /8 PM PDT/ Friday.
* IMPACTS...Heat related illnesses increase significantly during
extreme heat events. Overexposure can cause heat cramps and heat
exhaustion to develop and, without intervention, can lead to heat
stroke.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
An Extreme Heat Warning means that a period of very hot temperatures,
even by local standards, will occur. Actions should be taken to
lessen the impact of the extreme heat.
Take extra precautions if you work or spend time outside. When
possible, reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose-fitting clothing when possible and
drink plenty of water.
To reduce risk during outdoor work, the Occupational Safety and
Health Administration recommends scheduling frequent rest breaks in
shaded or air conditioned environments. Anyone overcome by heat
should be moved to a cool and shaded location. Heat stroke is an
emergency! Call 9 1 1.
Public cooling shelters are available in some areas. Consult county
officials for more details.
&&
$$
URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
1147 AM MST Tue Aug 18 2026
AZZ534-538-539-541-549-553>555-559-191000-
/O.CON.KPSR.XH.W.0008.000000T0000Z-260822T0300Z/
Aguila Valley-Tonopah Desert-Gila Bend-Cave Creek/New River-
Fountain Hills/East Mesa-Northwest Pinal County-West Pinal County-
Apache Junction/Gold Canyon-Sonoran Desert Natl Monument-
Including the cities of Fountain Hills, Apache Junction, Aguila, Gila
Bend, Tonopah, Wickenburg, Sentinel, Kaka, Hassayampa, Scottsdale,
Arlington, Casa Grande, Coolidge, Cactus Forest, Gladden, Florence,
and Wintersburg
1147 AM MST Tue Aug 18 2026
...EXTREME HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM MST FRIDAY...
* WHAT...Dangerously hot conditions. Afternoon temperatures 105 to
113 expected. Major Heat Risk.
* WHERE...Aguila Valley, Apache Junction/Gold Canyon, Cave Creek/New
River, Fountain Hills/East Mesa, Gila Bend, Northwest Pinal County,
Sonoran Desert Natl Monument, and Tonopah Desert.
* WHEN...Until 8 PM MST Friday.
* IMPACTS...Heat related illnesses increase significantly during
extreme heat events. Overexposure can cause heat cramps and heat
exhaustion to develop and, without intervention, can lead to heat
stroke.
* ADDITIONAL DETAILS...In Maricopa County, call 2-1-1 to find a free
cooling center, transportation, water and more.
https://www.maricopa.gov/heat
PRECAUTIONARY/PREPAREDNESS ACTIONS...
An Extreme Heat Warning means that a period of very hot temperatures,
even by local standards, will occur. Actions should be taken to
lessen the impact of the extreme heat.
Take extra precautions if you work or spend time outside. When
possible, reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose-fitting clothing when possible and
drink plenty of water.
To reduce risk during outdoor work, the Occupational Safety and
Health Administration recommends scheduling frequent rest breaks in
shaded or air conditioned environments. Anyone overcome by heat
should be moved to a cool and shaded location. Heat stroke is an
emergency! Call 9 1 1.
Public cooling shelters are available in some areas. Consult county
officials for more details.
&&
$$
URGENT - WEATHER MESSAGE
National Weather Service Las Vegas NV
416 AM PDT Tue Aug 18 2026
AZZ002-570-571-575-576-CAZ522-524>527-NVZ016-017-020-022-025-026-
191200-
/O.CON.KVEF.XH.W.0004.260818T1700Z-260822T0300Z/
Lake Havasu and Fort Mohave-Lake Mead - AZ side-Lake Mohave - AZ
side-Hualapai Mountains-Northwest Deserts-Death Valley National
Park-Eastern Mojave Desert-Morongo Basin-Cadiz Basin-San
Bernardino County-Upper Colorado River Valley-Northeast Clark
County-Western Clark and Southern Nye County-Las Vegas Valley-
Southern Clark County-Lake Mead - NV side-Lake Mohave - NV side-
Including the cities of Amargosa Valley, Temple Bar, Pahrump,
Stovepipe Wells, Moapa, Wikieup, Needles, Desert Rock, North Las
Vegas, Valentine, Searchlight, Yucca Valley, Golden Valley, Mesquite,
Hoover Dam, Primm, Desert Hills, Bullhead City, Vidal Junction, Las
Vegas, Yucca, Mountain Pass, Topock, Hualapai Peak, Lake Havasu City,
Kingman, Furnace Creek, Baker, South Cove,
Cal-Nev-Ari, Morongo Valley, Boulder City, Twentynine Palms,
Laughlin, Dolan Springs, Henderson, Indian Springs, Overton, Mitchell
Caverns, and Shoshone
416 AM PDT Tue Aug 18 2026 /416 AM MST Tue Aug 18 2026/
...EXTREME HEAT WARNING REMAINS IN EFFECT FROM 10 AM PDT /10 AM MST/
THIS MORNING TO 8 PM PDT /8 PM MST/ FRIDAY...
* WHAT...Dangerously hot conditions with temperatures up to 115 to
118 degrees expected through Death Valley and the lower Colorado
River Valley, with highs between 107 to 110 degrees elsewhere.
* WHERE...Portions of northwest Arizona, southeast California, and
southern Nevada.
* WHEN...From 10 AM PDT /10 AM MST/ this morning to 8 PM PDT /8 PM
MST/ Friday.
* IMPACTS...Heat-related illnesses increase significantly during
extreme heat events.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Drink plenty of fluids, stay in an air-conditioned room, stay out of
the sun, and check up on relatives and neighbors.
Do not leave young children and pets in unattended vehicles. Car
interiors will reach lethal temperatures in a matter of minutes.
Take extra precautions when outside. Wear lightweight and
loose-fitting clothing. Try to limit strenuous activities to early
morning or evening. Take action when you see symptoms of heat
exhaustion and heat stroke.
To reduce risk during outdoor work, the Occupational Safety and
Health Administration recommends scheduling frequent rest breaks in
shaded or air conditioned environments. Anyone overcome by heat
should be moved to a cool and shaded location. Heat stroke is an
emergency! Call 9 1 1.
Monitor the latest forecasts and warnings for updates.
&&
$$
CM
Heat Advisory
URGENT - WEATHER MESSAGE
National Weather Service Los Angeles/Oxnard CA
102 PM PDT Tue Aug 18 2026
CAZ038-088-343>345-351-353-371>373-375-376-379-380-548-210300-
/O.CON.KLOX.HT.Y.0013.000000T0000Z-260821T0300Z/
Cuyama Valley-Santa Clarita Valley-Southern Salinas Valley-San
Luis Obispo County Interior Valleys-San Luis Obispo County
Mountains-Santa Ynez Mountains Western Range-Santa Barbara County
Interior Mountains-Calabasas and Agoura Hills-Western San
Fernando Valley-Eastern San Fernando Valley-Santa Susana
Mountains-Southern Ventura County Mountains-Western San Gabriel
Mountains and Highway 14 Corridor-Eastern San Gabriel Mountains-
Los Angeles County San Gabriel Valley-
Including the cities of Lake Nacimiento, Woodland Hills, Santa
Clarita, Sunland, Carrizo Plain, Northridge, Creston, San Marcos
Pass, Burbank, Shandon, Warm Springs, Oat Mountain, Valencia, Mill
Creek, Templeton, Westlake Village, El Monte, Rose Valley, The
Angeles Crest Highway, Big Pine Mountain, Santa Margarita Lake,
Acton, San Rafael Mountain, Paso Robles, Newhall, New Cuyama, Mount
Baldy, Pomona, Figueroa Mountain, San Miguel, San Gabriel,
Chatsworth, Mount Wilson, Glendale, Topatopa Mountains, Pasadena, La
Panza Range, Atascadero, East Los Angeles, Matilija, Caliente Range,
Lake Castaic, Van Nuys, Wrightwood, Universal City, Malibu Lake, and
La Canada Flintridge
102 PM PDT Tue Aug 18 2026
...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM PDT THURSDAY...
* WHAT...High temperatures of 92 to 105 expected, with most areas
seeing peak heat on Wednesday and Thursday. Low temperatures are
expected to range from the upper 60s to lower 70s at lower
elevations to the mid 70s to lower 80s in the foothills and
mountains.
* WHERE...A portion of southwest California.
* WHEN...Until 8 PM PDT Thursday.
* IMPACTS...Hot temperatures may cause heat illnesses. Warmer than
normal low temperatures will add to the heat discomfort.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Drink plenty of fluids, stay in an air-conditioned room, stay out of
the sun, and check up on relatives and neighbors.
Take extra precautions when outside. Wear lightweight and loose
fitting clothing. Try to limit strenuous activities to early morning
or evening. Take action when you see symptoms of heat exhaustion and
heat stroke.
&&
$$
URGENT - WEATHER MESSAGE
National Weather Service San Diego CA
1156 AM PDT Tue Aug 18 2026
CAZ048-190500-
/O.NEW.KSGX.HT.Y.0009.260819T1700Z-260821T0300Z/
San Bernardino and Riverside County Valleys-The Inland Empire-
Including the cities of Ontario, Moreno Valley, Fontana, Corona,
Riverside, Rancho Cucamonga, and San Bernardino
1156 AM PDT Tue Aug 18 2026
...HEAT ADVISORY IN EFFECT FROM 10 AM WEDNESDAY TO 8 PM PDT
THURSDAY...
* WHAT...Temperatures up to 105 expected.
* WHERE...San Bernardino and Riverside County Valleys-The Inland
Empire.
* WHEN...From 10 AM Wednesday to 8 PM PDT Thursday.
* IMPACTS...Hot temperatures may cause heat illnesses.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Drink plenty of fluids, stay in an air-conditioned room, stay out of
the sun, and check up on relatives and neighbors.
&&
$$
Westerink
Lake Wind Advisory
URGENT - WEATHER MESSAGE
National Weather Service Hanford CA
500 PM PDT Tue Aug 18 2026
CAZ332-190600-
/O.CON.KHNX.LW.Y.0023.000000T0000Z-260819T0600Z/
Kern River Valley-
Including the cities of Lake Isabella and Kernville
500 PM PDT Tue Aug 18 2026
...LAKE WIND ADVISORY REMAINS IN EFFECT UNTIL 11 PM PDT THIS
EVENING...
* WHAT...West winds 10 to 20 mph with gusts up to 30 mph.
* WHERE...Kern River Valley.
* WHEN...Until 11 PM PDT this evening.
* IMPACTS...Strong winds and rough waves on area lakes will create
hazardous conditions for small craft.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Winds this strong can make driving difficult, especially for high
profile vehicles. Use extra caution.
&&
$$
BSO
