RSS FeedsExcessive Heat Safety
Heat related deaths outpace fatalities in several other severe weather categories. Based on a 10 year average from 1992-2001, excessive heat claimed 219 lives each year. By contrast, floods killed 88, tornadoes 57, lightning 52 and hurricanes 15.
Heat Index Chart
Click on the chart below to view a text table of values.
On average, about 175 Americans succumb to the taxing demands of heat every year. Our bodies dissipate heat by varying the rate and depth of blood circulation, by losing water through the skin and sweat glands, and as a last resort, by panting, when blood is heated above 98.6°F. Sweating cools the body through evaporation. However, high relative humidity retards evaporation, robbing the body of its ability to cool itself.
When heat gain exceeds the level the body can remove, body temperature begins to rise, and heat related illnesses and disorders may develop.
The Heat Index (HI) is the temperature the body feels when heat and humidity are combined. The chart above shows the HI that corresponds to the actual air temperature and relative humidity. (NOTE: This chart is based upon shady, light wind conditions. Exposure to direct sunlight can increase the HI by up to 15°F.)
(Due to the nature of the heat index calculation, the values in the tables below have an error of +/- 1.3F.)
Heat Related Links
- National Weather Service Pages
- Sites outside the National Weather Service
