When the METAR reports surface winds, what unit is typically used?

In METAR reports, surface winds are expressed in knots. This unit of measurement is standard in aviation and meteorology because it is based on nautical miles, which aligns with the practices used in air and maritime navigation. The use of knots allows for a consistent and easily understandable representation of wind speed for pilots and meteorologists.

Knots are particularly useful in aviation, as they provide a direct correlation to the distances covered over time which is critical for flight planning and safety. With a knot defined as one nautical mile per hour, it simplifies calculations related to aircraft speed and fuel consumption during flight.

Other units like miles per hour (used more commonly in land transport), kilometers per hour, and feet per second are not standard in aviation contexts, which is why they are not used in METAR reports.