CalcuNation

Heat Index Calculator (Fahrenheit)

Calculate the heat index in fahrenheit with this online calculator.

Temp (Fahrenheit):
Humidity): %
Fill in the temperature and humidity to determine approximate heat index.

This calculation is meant for air temperatures greater than 80 degrees fahrenheit and humidity greater than 50%.

How do you determine heat index?

To calculate heat index, use the equation:

Heat Index = A + (B x T) + (C x R) + (D x T x R) + (E x T2) + (F x R2) +
(G X T2 x R) + (H x T x R2) + (I x T2 x R2)

T = Ambient Temperature (Fahrenheit)
R = Relative Humidity (%)
A = -42.379
B = 2.04901523
C = 10.14333127
D = -0.22475541
E = -6.83783 x 10-3
F = -5.481717 x 10-2
G = 1.22874 x 10-3
H = 8.5282 x 10-4
I = -1.99 x 10-6

Example: When the ambient temperature (in fahrenheit) is 92 degrees, relative humidity is 65%, the effective heat index is:

Heat Index = -42.379 + ( 2.04901523 x 92) + ( 10.14333127 x 65) +
(-0.22475541 x 92 x 65) + ( -6.83783 x 10-3 x 922) + ( -5.481717 x 10-2 x 652) + ( 1.22874 x 10-3 X 922 x 65) + ( 8.5282 x 10-4 x 92 x 652) + ( -1.99 x 10-6 x 922 x 652)

Approximate Heat Index = 108.3 Degrees Fahrenheit

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