For an accurate wind map, you will need to record the energy output from different wind speeds before taking the annual wind level average measured by an anemometer at a typical 33ft (10m) height.

Alternatively, arrange a few cups in such a way that greater wind speed will make them spin faster. Connect the spinning shaft to a device that detects speed and feed the output to a recorder or data logger. Collect this data over long periods to plot the "Rayleigh distribution" curve. The curve displays the frequency of occurrence of each wind speed. The highest point found on this distribution curve is the most frequent wind speed. Over a 12-month recording period, you will get the average annual wind speed and accurate data for any time of the year.

Wind speed mappings come in speed and "power class" formats. The typical wind speed rating is measured in meters per second but can be in other units.

There is also a power class – numbered from 1 to 7 – to indicate the wind's relative energy based on average yearly wind speeds for a region. Power class 1 is unacceptable for wind turbines. The power class numbers are determined by various local geographical factors like lakes, hills, mountains and trees. Another factor affecting the mapping accuracy is the distance between the recording site and your location. Wind mapping may be functional but is not foolproof.

Maps are available which detail wind speed for annual, seasonal and monthly periods. These maps are compiled by and for the government for a variety of purposes such as crop planting, weather forecasting and wind turbine installations. 

Wind atlases are available online at:

United States: rredc.nrel.gov/wind/pubs/atlas/

Canada: www.windatlas.ca/en/index.php