In the Southwestern United States, record-setting heat has killed at least four people and fueled more than a dozen wildfires. In Los Angeles, thousands lost power Monday as air conditioners overwhelmed the power grid. Outside the city, two massive wildfires blazed through at least 4,500 acres in the San Gabriel Mountains, forcing at least 750 people to evacuate. It was 118 degrees Fahrenheit in Phoenix, Arizona, on Sunday, a daily record. Last month was the hottest May ever recorded, the 13th straight month to set a new record amid human-caused climate change.