It’s a dry heat, Phoenix residents like to say about Arizona’s hot weather. That bravado may vanish as the thermometer flirts with 120 degrees this weekend.

Phoenix won’t be alone in the oven. A strengthening 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 heat stroke.