The extreme heat in the Southeast could lead to heat-related illnesses, especially for vulnerable populations such as the elderly, children, and those without air conditioning. The combination of high temperatures and humidity increases the risk of dehydration and heat exhaustion. In the Midwest, the unseasonably cool temperatures may require residents to adjust to colder-than-usual conditions for mid-June. The stark contrast in weather patterns highlights the variability of conditions across the U.S. this weekend.