Weather forecasting begins with three types of weather observations: Surface observations give local weather useful for airport runways. Upper air observations come from weather balloons and pilots reporting on upper atmospheric conditions. Radar observations show precipitation, wind speed, and weather systems.

The Federal Aviation Administration (FAA) identifies three distinct types of weather information essential for flight safety: Observations, Analysis, and Forecasts. Observations are raw, real-time data collected by sensors or human observers, such as METARs (surface observations), PIREPs (pilot reports), and satellite imagery. Analysis involves the interpretation or "enhanced depiction" of that observed data, where meteorologists or automated systems create products like surface analysis charts to show pressure systems and fronts. Forecasts are predictions of future weather conditions based on mathematical models and current observations; these include TAFs (Terminal Aerodrome Forecasts) and SIGMETs (Significant Meteorological Information). Together, these three categories allow pilots to understand what the weather is doing right now, why it is happening, and what it is expected to do during their flight. This structured approach is fundamental to pre-flight planning and in-flight decision-making to avoid hazardous conditions like icing or severe turbulence.