Heat advisories are in effect for over 163 million people across the Midwest and Southeast, according to the National Weather Service. The advisories cover a significant portion of the East Coast and are expected to remain in place through much of the weekend. Residents are urged to take precautions against the heat, including staying hydrated, limiting outdoor activities during peak heat hours, and checking on vulnerable individuals such as the elderly and those with pre-existing health conditions. The National Weather Service recommends seeking air-conditioned environments whenever possible to avoid heat-related illnesses.