A sweltering heat wave across the Southwest is raising the risk of deaths of children in hot cars, a common topic in the United States where nearly 40 children die each year. The majority of these deaths are under the age of 3, and most are left by parents or caregivers by complete accident. The National Weather Service in Los Angeles has warned of the potential for children or pets to be left in cars earlier than usual due to heat. The heat wave began in Southern California on March 17 and is expected to expand throughout the week. Over 18 million people are under extreme heat warnings due to the weather wave.