From Wikipedia, the free encyclopedia:
The ICAO airport code or location indicator is a four-letter code designating aerodromes around the world. These codes are defined by the International Civil Aviation Organization, and published in ICAO Document 7910: Location Indicators.
ICAO codes are also used to identify other aviation facilities such as weather stations, International Flight Service Stations or Area Control Centers, whether or not they are located at airports.
Appropriate ICAO Station IDs that can be used with NOAA's National Weather Service can be found by going here: NOAA's National Weather Service, typing in a "City, St" or ZIP code, then noting the ICAO Station ID shown in the Current conditions section. It will be the code inside parentheses at the end of the location name.