TEMP is a set of World Meteorological Organization (WMO) alphanumerical codes used for reporting weather observations of the upper regions of the atmosphere

Atmosphere

An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

 made by weather balloons

Weather balloon

A weather or sounding balloon is a balloon which carries instruments aloft to send back information on atmospheric pressure, temperature, humidity and wind speed by means of a small, expendable measuring device called a radiosonde...

released from the surface level (either at land or at sea). The WMO designates the FM-35 numerical code for surface TEMPs and the FM-36 numerical code for ship-based TEMPs.