The Kestrel 4000 is a new pocket size weather instrument. It measures air temperature in degrees, percent humidity, dew point, and wet bulb temperature. Wind speed is measured in miles per hour. It stores the minimum, maximum, and average wind speed. It also measures wind chill, heat index, barometric pressure, altitude, and density altitude. The Kestrel 4000 is a new improved pocket weather station that measures barometric pressure.