The heat wave poses significant risks to millions of residents across the central and eastern U.S., particularly those in urban areas where heat indices will exceed 100°F (37.8°C). Vulnerable populations, such as the elderly and those without air conditioning, are at heightened risk of heat-related illnesses. Additionally, nighttime temperatures in the 70s (21-26°C) will provide little relief, increasing the potential for heat stress. In the West, flash flooding from monsoonal storms has already caused evacuations in Arizona and Utah, with further risks of flooding and severe weather expected in parts of Arizona, Utah, and Colorado.