A weather monitoring and prediction system that uses a fleet of aircraft to obtain data. Each aircraft has a local air data system that facilitates the measurement, recordation, and transmittal of local atmospheric data such as barometric pressure, and the corresponding temporal, positional, and altitudinal data. The data is electronically transmitted from each aircraft to a ground based processing system where it is stored. The data may then be transmitted to subscribing users such as aircraft, other weather data systems or to air traffic control centers in either a compiled form or in a raw form. Another embodiment also provides for measuring barometric pressure as a function of altitude at an in-flight aircraft.