What does "BECMG" signify in a TAF?

In the context of a Terminal Aerodrome Forecast (TAF), "BECMG" is an abbreviation that indicates a change is expected to happen over a specified time period. The term stands for "becoming," and it is used to signify that the weather conditions are transitioning to a specific state or condition described in the forecast.

For example, if the TAF states "BECMG 1212/1214," it signifies that there will be a gradual transition to the weather conditions specified in that timeframe. This could relate to changes in visibility, wind, precipitation, or other atmospheric variables, illustrating that a particular weather situation is expected to evolve.

The understanding of "BECMG" is crucial for pilots and aviation meteorologists, as it helps them prepare for and navigate the expected changes in weather conditions. This contributes to flight safety and operational planning at airports.