The Brief Extreme heat warnings and heat advisories remain in effect across most of Arizona, with Phoenix reaching record temperatures of 115 degrees on Sunday. Sunday was another day of extreme heat across Arizona. Extreme heat warnings and heat advisories will remain in effect across the majority of Arizona through Monday. Friday and Saturday:All of southern, central, and western Arizona were under extreme heat warnings. The Grand Canyon, below 4,000 feet, is also under the extreme heat warning through Sunday.