Eleven of the victims since Saturday were homeless, and the other two were elderly women, including one whose home cooling system wasn't on, police said Wednesday.
By comparison, the Arizona Department of Health Services documented 34 heat-related deaths among all Arizona residents last year. The number of illegal immigrants killed by heat-related illnesses while trying to cross the desert on the U.S.-Mexico border are counted separately.
But the blistering heat wave isn't just being felt in Phoenix. It's hot in most of the country.
"It's been steamy from the Gulf Coast all the way to New England, featuring afternoon thunderstorms throughout the region," says CBS News Meteorologist George Cullen.
A week-long heat wave has hit California's San Joaquin Valley, reports CBS News Correspondent Jerry Bowen. One farm worker is dead from heat exhaustion there. And in Los Angeles, three men nearly suffocated in the closed car in which they were sleeping.
In New York, people coping with the summer heat broke the region's record for electricity usage. Con Edison said that by 4 p.m. Monday, customers in New York City and Westchester County had hit an all-time peak, consuming 12, 361 megawatts.
New Englanders also set a new record for electricity usage on Tuesday. Electricity use in ISO New England Inc.'s six-state region peaked at an average 26,749 megawatts between 2 p.m. and 3 p.m., breaking the previous record of 25,348 megawatts set on Aug. 14, 2002.
Phoenix has endured above-average temperatures every day since June 29, with a peak of 111 degrees Fahrenheit (44 degrees Celsius) on Tuesday, and a high of 108 F (42 C) was forecast Wednesday. Even during the coolest part of the day, the temperature descended only to 89 F (32 C) Wednesday morning.
The spike in deaths prompted the mayor on Monday to ask for bottled water donations. Bill Manson, development coordinator for Central Arizona Shelter Services, said a number of companies and individuals had been donating water and organizing drives to collect bottled water.