When you hear the high temperature of the day from your local TV weathercaster, that information came from an Automated Surface Observing Systems (ASOS) machine from your local airport. ASOS is installed at more than 900 airports across the country, where they make observations.
Federally funded, ASOS is a joint program of the National Weather Service, the Federal Aviation Administration, and the Department of Defense. The ASOS systems serve as the nation's primary surface weather observing network.
The many sensors that comprise ASOS detect different weather elements and can update the official weather observation up to 12 times each hour. ASOS works non-stop, 24 hours a day, every day of the year.