The National Weather Service has issued an extreme heat watch for parts of California, Nevada, and Arizona, effective Monday, March 16, 2026. Record-breaking temperatures are anticipated, posing a significant risk of heat-related illnesses. In California, areas like the Coachella Valley and San Diego County deserts could see temperatures soaring to between 105°F and 110°F, which is 20 to 30 degrees above average. Arizona is expected to reach 109°F in its southwest and south-central regions. Nevada's Lake Mead National Recreation Area might experience highs of 106°F.