The extreme heat will primarily affect those in desert and mountainous areas, where temperatures in the triple digits (above 100°F or 37.8°C) are expected. Vulnerable populations, such as the elderly, children, and individuals with pre-existing health conditions, are at heightened risk of heat-related illnesses. The lack of significant overnight cooling could further strain those without access to air conditioning or cooling centers. Outdoor workers and hikers should also exercise caution to avoid heat exhaustion or heatstroke.