What does a sustained wind of 20 knots indicate?

A sustained wind of 20 knots is classified as moderate winds. Sustained winds refer to the average wind speed over a specific period, typically measured over one minute. In meteorological terms, wind classifications often categorize speeds as follows: light winds are generally considered to be less than 10 knots, moderate winds range from about 10 to 20 knots, and strong winds are typically over 20 knots.

Thus, a sustained wind of 20 knots indicates that the wind is at the higher end of the moderate range, without reaching the threshold into strong winds. It's important to note that sustained winds can affect aviation operations, and understanding these classifications helps pilots and other aviation personnel gauge the potential impact on flight safety and performance.