METAR is a format for reporting weather information. A METAR weather report is predominantly used by pilots in fulfillment of a part of a pre-flight weather briefing, and by meteorologists, who use aggregated METAR information to assist in weather forecasting.
METARs can be expressed concisely using so-called aviation flight categories, which indicates what classes of flight can operate at each airport by referring to the visibility and ceiling in each METAR. Four categories are used:
|VFR||> 5 mi||and > 3,000 ft|
|Marginal VFR||Between 3 and 5 mi||and/or Between 1,000 and 3,000 ft|
|IFR||1 mi or more but less than 3 mi||and/or 500 ft or more but less than 1,000 ft|
|Low IFR||< 1 mi||and/or < 500 ft|