The western United States is currently experiencing an extreme heat wave, marked by record-breaking temperatures for this time of year. A strong high-pressure system is preventing precipitation and trapping heat, particularly affecting cities in the Desert Southwest like Palm Springs and Phoenix, where temperatures have soared into the triple digits. Phoenix has even recorded its earliest 100-degree day ever. The National Weather Service has issued widespread extreme heat warnings and advisories for major cities including San Francisco, Los Angeles, San Diego, Palm Springs, Las Vegas, Phoenix, and Tucson. These hazardous conditions are expected to persist through the weekend and potentially into early next week.