It's about to get really hot in the Southwest, and health officials want people to stay alert.
Temperatures are expected to reach record highs this week. Forecasters say it could get up to 120 degrees in Tucson and Phoenix. The National Weather Service has issued excessive heat warnings for both areas.
The region is no stranger to heat waves, and despite record-breaking highs in some areas this year, past years have been much harder.
In 2013, it got so hot in California that a man reported seeing his running shoes melt. The temperature was 128 degrees. Almost a decade earlier in 2005, a similar heat wave killed 17 people in Las Vegas. The high was 117 degrees.
Las Vegas is predicted to reach 117-degree highs again this year. Death Valley is just one degree short of its record with a high of 127.
These high temperatures are caused by an aptly named weather phenomenon: "heat domes."
In a heat dome, high pressure seals the atmosphere and prevents hot air from escaping. Beyond high temperatures, experts also say heat domes trap pollution and lower air quality.
Health officials recommend people stay hydrated, limit time outside and recognize the symptoms of heat exhaustion and stroke.