Wind

Wind Direction

Wind direction always signifies where the wind is coming FROM, and is always referenced to true north.

Wind Speed

Determined by averaging the wind speed over the previous: 

• 2-minute period, in the United States

• 10-minute period outside the United States

In the United States, knots (nautical miles per hour) is always used, except in reference to public forecasting where mph is used instead.

Important Wind Characteristics

Wind Shift - When wind direction changes by 45 degrees or more in less than 15 minutes with sustained winds of 10 kt or more throughout the wind shift.

Wind Squall - Sudden increase of wind speed by at least 16 kt, rising to 22 kt or more and lasting for at least one minute.

• May be associated with front or outflow passage.

Gale - A surface wind with a mean speed of 34 kt or more (using a 10-minute average).

Veering - A clockwise change in wind direction with time or with height; e.g. south to west.

• Optimal for the production of severe weather

Backing - A counterclockwise change in wind direction with time or with height; e.g. south to east.

Beaufort Wind Scale