High temperatures and high humidity can cause serious illness, particularly among children younger than age 5 or people older than 64; those with a chronic medical or mental-health condition; those on medications; people confined to their beds or unable to leave their homes; or people who are overweight.

Health officials recommend:

-- Use an air conditioner if you have one, or go to a cooler place such as an air-conditioned store, mall or movie theater, or cooling center.

-- Fans can help if the air is not too hot, but they work best at night to bring in cooler air from outside. Use a fan only when the air conditioner is on or windows are open.

-- Drink plenty of water or other fluids. Avoid beverages containing alcohol, caffeine or high amounts of sugar.

-- Stay out of the sun. If outside, wear lightweight, light-colored, loose-fitting clothing that covers as much skin as possible; wear a hat to protect the face and head; and use sunscreen.