The Brief Phoenix reached 111 degrees as extreme heat warnings remain in effect across Arizona through Sunday. Temperatures are turning up across the deserts of Arizona – extreme heat warnings are in effect for Phoenix through Sunday. Extreme heat warnings will begin at 10 a.m. for the Phoenix foothills and surrounding mountains, the Grand Canyon, southern and western Arizona. Friday will be an even hotter day across the state, with even more extreme heat warnings going into effect for the mountains of central Arizona, including Payson, Camp Verde and Sedona, as well as northern Arizona in Page and Lees Ferry. These storms can cause interruptions in services, such as water, power, and gas," stated Captain Ashley Losch of the Glendale Fire Department.