Forecasters are posting notices of dangerous heat in southern Nevada, southeastern California and southern and western Arizona for Tuesday and the next day or two.
The National Weather Service issued excessive heat warnings and watches for desert areas that include the cities of Phoenix, Tucson, Las Vegas and El Centro, Calif.
Forecasters said high temperatures in metro Phoenix may reach 116 degrees while Las Vegas could hit 113 degrees, creating a threat of heat-related illnesses.