The expansion of extreme heat seasons poses significant risks to public health, agriculture, and infrastructure. Heat events outside their usual season are particularly dangerous as they catch communities unprepared, with cooling centers and emergency plans often not in place. In regions like Phoenix, Arizona, where extreme heat days have increased dramatically, the prolonged heat season has led to higher heat-related mortality rates. Additionally, the overlap of extreme heat with other seasonal hazards, such as wildfires in the western U.S. or hurricanes in the Southeast, amplifies the risks. Humid heat, which limits the body's ability to cool itself, is especially hazardous to human health, while dry heat can severely impact crops and ecosystems.