The chart below lists the apparent temperatures (heat index)
in degrees Fahrenheight (F). The chart is read by finding
the air temperature on the left vertical column and the
Relative Humidity (RH) across the top horizontal row and
reading where these values intersect. If the ambient temperature
is 90 degrees and the RH is 60 percent, then the apparent
temperature is 100 degrees.
Effects of Heat
Heat Index
Possible Heat Disorder
80-90 F
Fatigue possible
90-105 F
Sunstroke, heat cramps, heat exhaustion possible
105-130 F
Sunstroke, heat cramps, heat exhaustion likely -
Heat stroke possible
www.weather.gov 
