Lake Michigan coastal dunes are subject to winds that vary seasonally in strength and direction.

Overall (Annual) Wind Patterns
Mean monthly wind speeds recorded at Muskegon, MI, are between 4 and 6 m/s (9-12 mph). Peak gusts greater than 22 m/s (50 mph) have been recorded in every month of the year. The winds are more frequently from the west than the east throughout the year.

To read the windrose (right), look for the percentage of time (indicated by dashed circles) that winds come from a specific direction (such as west). Colors indicate the speeds of the winds from the indicated directions (see color key).

The windrose is based on thirty years (1961-1990) of wind data collected in Muskegon by the National Weather Service.

Wind speed is a defining variable for coastal dunes. For sand to move, wind speeds must exceed a threshold level related to sand grain size. This threshold level is roughly 5-6 m/s for Lake Michigan dune sands. The amount of sand movement is also related to wind speed: the volume of sand transported by wind increases exponentially with increases in wind speed. More sand will move in a single storm with high winds than will move with months of wind speeds just above the threshold.

Strong winds do not automatically produce sand movement. If surface sand grains are affected by surface moisture, snow, ice, ground freezing, vegetation or other complicating variables, sand movement will be greatly reduced or halted completely.