San Bernardino County, CA

Alerts

Warning Area
Advisory Area
County Line

Alerts are listed in order of start time and level of severity. Click on the alert title to read details for each alert.

In effect from Sunday 07/26 11:14 AM PDT – Monday 07/27 8:00 PM PDT

Issued by NWS San Diego CA

What

Dangerously hot conditions with high temperatures of 100 to 109 and low temperatures in the low 70s to low 80s.

Where

Apple and Lucerne Valleys.

When

Until 8 PM PDT Monday.

Impacts

Heat related illnesses increase significantly during extreme heat events.

Additional Details

Areas of major HeatRisk. Elevated low temperatures will limit overnight relief from the heat.

What to Do

Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.


Areas Impacted

  • Apple and Lucerne Valleys

Tips to Stay Safe

An Extreme Heat Warning means that extremely dangerous heat conditions are happening now or soon. You must take precautions to protect yourself and others from extreme heat. 

  • Stay inside in air conditioning if possible. If you don’t have air conditioning, go to a library, mall, or local cooling center. 
  • Drink plenty of water to stay hydrated, and wear loose, light-colored clothing. 
  • Check on friends, family, and neighbors, especially those who do not have air conditioning or spend much of their time alone. 
  • Reschedule outdoor activities for a cooler day.
  • If you must be outdoors, take longer and more frequent breaks in the shade or air conditioning, and avoid the hottest parts of the day.
  • Bring pets indoors if possible. If pets are left outside, make sure they have shade and plenty of cool water. 
  • Make sure you know the signs of heat-related illness and how to respond.

In effect from Sunday 07/26 11:59 AM PDT – Monday 07/27 8:00 PM PDT

Issued by NWS Phoenix AZ

What

Dangerously hot conditions. Afternoon temperatures 104 to 116. Major Heat Risk. Overexposure can cause heat cramps and heat exhaustion to develop and, without intervention, can lead to heat stroke.

Where

Mostly rural portions of southwest Arizona and southeast California, including Joshua Tree National Park.

When

Until 8 PM MST /8 PM PDT/ Monday.

Impacts

Heat related illnesses increase significantly during extreme heat events.

What to Do

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.


Areas Impacted

  • Kofa
  • Central La Paz
  • Southeast Yuma County
  • Gila River Valley
  • Joshua Tree NP West
  • Joshua Tree NP East
  • Imperial County Southwest
  • Salton Sea
  • Chuckwalla Mountains
  • Imperial County Southeast
  • Imperial County West
  • Chiriaco Summit

Tips to Stay Safe

An Extreme Heat Warning means that extremely dangerous heat conditions are happening now or soon. You must take precautions to protect yourself and others from extreme heat. 

  • Stay inside in air conditioning if possible. If you don’t have air conditioning, go to a library, mall, or local cooling center. 
  • Drink plenty of water to stay hydrated, and wear loose, light-colored clothing. 
  • Check on friends, family, and neighbors, especially those who do not have air conditioning or spend much of their time alone. 
  • Reschedule outdoor activities for a cooler day.
  • If you must be outdoors, take longer and more frequent breaks in the shade or air conditioning, and avoid the hottest parts of the day.
  • Bring pets indoors if possible. If pets are left outside, make sure they have shade and plenty of cool water. 
  • Make sure you know the signs of heat-related illness and how to respond.

In effect from Sunday 07/26 3:42 PM PDT – Monday 07/27 8:00 PM PDT

Issued by NWS Las Vegas NV

What

Dangerously hot conditions expected. Afternoon temperatures in the desert valleys will climb into the 108 to 114 degree range, and may exceed 115 along the Colorado River Valley and 120 in Death Valley. Overnight lows generally 80 to 95 degrees.

Where

Portions of northwest Arizona, southeast California, and southern Nevada including the Greater Mojave Desert region.

When

Until 8 PM PDT /8 PM MST/ Monday.

Impacts

Heat related illnesses increase significantly during extreme heat events.

What to Do

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.


Areas Impacted

  • Lake Havasu and Fort Mohave
  • Lake Mead - AZ side
  • Lake Mohave - AZ side
  • Northwest Deserts
  • Death Valley National Park
  • Western Mojave Desert
  • Eastern Mojave Desert, Including the Mojave National Preserve
  • 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

Tips to Stay Safe

An Extreme Heat Warning means that extremely dangerous heat conditions are happening now or soon. You must take precautions to protect yourself and others from extreme heat. 

  • Stay inside in air conditioning if possible. If you don’t have air conditioning, go to a library, mall, or local cooling center. 
  • Drink plenty of water to stay hydrated, and wear loose, light-colored clothing. 
  • Check on friends, family, and neighbors, especially those who do not have air conditioning or spend much of their time alone. 
  • Reschedule outdoor activities for a cooler day.
  • If you must be outdoors, take longer and more frequent breaks in the shade or air conditioning, and avoid the hottest parts of the day.
  • Bring pets indoors if possible. If pets are left outside, make sure they have shade and plenty of cool water. 
  • Make sure you know the signs of heat-related illness and how to respond.

In effect from Wednesday 07/22 10:00 AM PDT – Monday 07/27 8:00 PM PDT

Issued by NWS San Diego CA

The Heat Advisory has been replaced. Please see the latest information from NWS San Diego CA on this developing situation.

What to Do

Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.


Areas Impacted

  • San Bernardino and Riverside County Valleys-The Inland Empire

Tips to Stay Safe

A Heat Advisory means dangerous heat conditions are happening now or soon. Take action before, during and after the heat to stay safe. 

  • Stay in air-conditioned spaces if possible. Find cooling centers or places with AC in your community that you can go to, like libraries or shopping malls. 
  • Stay hydrated and stock up on clean drinking water to get you through multiple days of heat.
  • Reschedule outdoor activities for cooler times of the day, and take breaks in the shade or air conditioning.
  • Cover windows with curtains or shades, or use window reflectors designed to reflect heat back outside. 
  • Check on friends, family, and neighbors, especially those who do not have air conditioning or spend much of their time alone. 

Make sure you know the signs of heat-related illness and how to respond.

In effect from Sunday 07/26 11:14 AM PDT – Monday 07/27 8:00 PM PDT

Issued by NWS San Diego CA

What

Dangerously hot conditions with high temperatures in the mid 90s to 103 and low temperatures in the mid 60s to low 70s.

Where

San Bernardino and Riverside County Valleys-The Inland Empire.

When

Until 8 PM PDT Monday.

Impacts

Hot temperatures may cause heat illnesses.

What to Do

Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.


Areas Impacted

  • San Bernardino and Riverside County Valleys-The Inland Empire

Tips to Stay Safe

A Heat Advisory means dangerous heat conditions are happening now or soon. Take action before, during and after the heat to stay safe. 

  • Stay in air-conditioned spaces if possible. Find cooling centers or places with AC in your community that you can go to, like libraries or shopping malls. 
  • Stay hydrated and stock up on clean drinking water to get you through multiple days of heat.
  • Reschedule outdoor activities for cooler times of the day, and take breaks in the shade or air conditioning.
  • Cover windows with curtains or shades, or use window reflectors designed to reflect heat back outside. 
  • Check on friends, family, and neighbors, especially those who do not have air conditioning or spend much of their time alone. 

Make sure you know the signs of heat-related illness and how to respond.

In effect from Sunday 07/26 11:14 AM PDT – Monday 07/27 8:00 PM PDT

Issued by NWS San Diego CA

What

High temperatures in the mid 80s to upper 90s and lows in the mid 60s to mid 70s below 6500 ft.

Where

Riverside County Mountains and San Bernardino County Mountains.

When

Until 8 PM PDT Monday.

Impacts

Hot temperatures may cause heat illnesses.

What to Do

Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.


Areas Impacted

  • San Bernardino County Mountains
  • Riverside County Mountains

Tips to Stay Safe

A Heat Advisory means dangerous heat conditions are happening now or soon. Take action before, during and after the heat to stay safe. 

  • Stay in air-conditioned spaces if possible. Find cooling centers or places with AC in your community that you can go to, like libraries or shopping malls. 
  • Stay hydrated and stock up on clean drinking water to get you through multiple days of heat.
  • Reschedule outdoor activities for cooler times of the day, and take breaks in the shade or air conditioning.
  • Cover windows with curtains or shades, or use window reflectors designed to reflect heat back outside. 
  • Check on friends, family, and neighbors, especially those who do not have air conditioning or spend much of their time alone. 

Make sure you know the signs of heat-related illness and how to respond.

Briefings

No recent briefing available

From the Forecaster

Monday Highs

Created by the NWS San Diego WFO

Similar temperatures Tuesday, and Wednesday.

A map of forecasted high temperatures for Southern California for July 27th, 2026.

Dangerous Heat

Created by the NWS Las Vegas WFO

Temperatures increase over the coming days, resulting in dangerous heat across the Mojave Desert Thursday through Monday. Anomalously warm overnight lows will greatly limit overnight relief while high temperatures run around 5 degrees above normal.

An Extreme Heat Warning has been issued for San Bernardino, Clark, southern Nye, southern Mohave, and eastern Inyo counties from Thursday through Monday.  Limit outside during the heat of the day: 10 am to 7 pm.  Stay hydrated with water and sports drinks.  Protect yourself from the sun with sunscreen, sunglasses, and hats.  Wear lightweight, light colored clothing.

Extreme Heat Warning

Created by the NWS Phoenix WFO

Temperatures will cool a couple degrees during the beginning of the week before leveling off during the middle of the week. Lower desert high temperatures will reach 106-115 degrees, while lows will be in the upper 80s to middle 90s. With temperatures cooling HeatRisk will decrease to widespread Moderate with some areas of Major. An Extreme Heat Warning is in effect for all of the lower deserts through Monday evening. The Extreme Heat Warning was extended for the Phoenix Metro, Lower CO River Valley, and Imperial Valley through Wednesday.

Graphic displaying a map of the extreme heat warnings shown in magenta. The map on the top left is for the areas through Monday and the map on the top right is for the areas on Tuesday and Wednesday. Forecast highs/lows are in the top middle and heat safety information is shown across the bottom.

Seven-day Weather Risk Overview

The graphic shows the daily risk summary for 7 days. Daily risk is based on highest risk factor for that day.

risk level
out of 10
out of 10
out of 10
out of 10
out of 10
out of 10
out of 10
table legend
No risk
Low risk
High risk

Weather Forecasting Office

Phoenix Forecast Office

Find a Forecast