National Weather Service United States Department of Commerce

Dangerous Heat Persists in the Southern U.S.;

Heat advisories and Excessive Heat Warnings persist across the Southern Plains and the Lower Mississippi Valley. Conditions should slowly improve in these area by Thursday. Severe storms and localized areas of flash flooding may occur across parts of the mid Mississippi Valley and portions of the southern and central High Plains. Read More >

Meteorological Calculator
(Thanks to Ron Murphy, NWS Binghampton, NY and Bryan Ruby, NWS Sioux Falls, SD for writing some of these scripts.)

Temperature Conversion
Enter a number then click on the appropriate number to see the result.
(o F)
(o C)

Windchill Calculation
Enter in the air temperature (Tair) in degrees Fahrenheit and wind speed in mph, then click on the Calculate WC to compute the windchill (WC). (Note: Wind Chill Temperature is only defined for temperatures at or below 50 degrees F and wind speeds above 3 mph.)
Tair Wind
Index Index
More information about the windchill equation.

Relative Humidity Calculation
Enter in the air temperature (Tair) and dew point temperature (Tdp) in degrees Fahrenheit (oF) then click on the Calculate RH to compute the relative humidity (RH).
Tair Tdp

Heat Index Calculation
Enter in the air temperature (Tair) in degrees Fahrenheit and relative humidity (RH) in percent (without the % sign), then click on the Calculate HI to compute the heat index (HI).
Tair RH Tdp=
Tair Tdp RH=
More information about the heat index equation.

Wind Speed Conversion
Enter a wind speed in the box below...then select "convert".
mph mph
knots knots
m/s m/s
ft/s ft/s
km/h km/h

Station Pressure Calculation
What is the current altimeter (inches)?
What is the station elevation? (feet)
The Station Pressure in inches is:
The Station Pressure in millibars is:
The Pressure Altitude is (feet):