(National Weather Service)
What is the Heat Index?
Many residents of the northeast realize that warm, dry
air seems more comfortable than warm, very moist air (unless it is too dry). An
extremely humid, warm day makes one think the temperature is higher than it
really is, while an extremely hot, dry day may seem to be cooler than the
One approach to describing the combined effects of
temperature and humidity is the heat index. To alert the public to the dangers
of exposure to extended periods of heat and the added effects of humidity, the
NationalWeather Service has developed a "Heat Index" table.
To determine the heat index, find the temperature across
the top of the table and the relative humidity down the left-hand side. Where
the two intersect is the heat index.