ALT Excessive Heat: Why is excessive heat so dangerous? Heat becomes especially dangerous if it lingers for more than one day. Hot days and warm nights don’t give our bodies time to cool down. Heat islands can intensify extreme hot weather, which can cause breathing problems, heat cramps, heat stroke, and may lead to illness or even death. What can you do? Check on your friends, family and neighbors during heat waves. Wear light, loose-fitting clothing and drink water often. Don't wait until you are thirsty. Avoid unnecessary hard work or activities if you are outside or in a building without air-conditioning. Stay in an air-conditioned area. Air conditioning is the strongest protective factor against heat-related illness.