A ridge of high pressure lifting out of Mexico is on course to also scorch other parts of Arizona and southeast California, bringing potentially record-shattering temperatures.
Though accustomed to triple digits, the upcoming heat spell is a rarity in Phoenix, a desert metropolis of 1.5 million people, raising concerns of heatstroke.
Temperatures are predicted to hit 118 degrees in Phoenix on Sunday and peak at 119 degrees Monday.
Extreme heat is likely to become more common, scientists say, blaming man-made greenhouse gas pollution.