Record heat in the Phoenix metro area this week also led to near-record electricity use by Arizona Public Service customers.
Officials with the state's largest utility company say APS customer demand reached 7,320 megawatts on Tuesday.
That set the peak for the most electricity used at the same time so far this year.
APS's record for peak demand is 7,363 megawatts, set on June 20, 2017.
For each of the first three days this week, APS customers used about twice as much energy as they do on an average winter day.
APS serves about 2.7 million people in 11 of Arizona's 15 counties.