http://www.bt.cdc.gov/disasters/extremeheat/heattips.asp
Centers for Disease Control and Prevention, U.S. Department of Health and Human Services
This fact sheet provides weather tips for preventing heat-related illness. Tips include staying indoors and, if at all possible, staying in an air-conditioned place; wearing lightweight, light-colored, loose-fitting clothing; limiting outdoor activity to morning and evening hours; and more.