People think they can handle anything. Most in danger are the very young, the elderly and people taking over the counter cold remedies, certain heart medications and almost all psychiatric drugs. All have a drying effect on the body, Dr. Iserson says. This is how you can really find out just how hot it is out there. The Heat Index combines the effects of heat and humidity.
Hot temperatures feel even hotter when it is humid.
The National Weather Service has devised the Heat Index for shady, light wind conditions. The heat index does not account for strong winds with very hot dry air, which can be hazardous because of the extremely rapid dehydration that can occur. The Heat Index shows the effects of the combination of heat and humidity. The apparent temperature is the heat or temperature your body feels. To use the chart, locate the temperature along the top row and the humidity along the left-hand column.