Predominant Wind Direction

The VWS software determines the predominant wind direction from the amount of time that the wind vane is pointed in each direction, like in the pie-chart below, which are the values from my site within the last 30 minutes.

This does not work too well here, because often there is no wind. Nothing moves, not even a leaf on a tree. The vane could stay pointed NW for hours when there is no wind and then a breeze may come up for an hour from the south. The predominant direction will be recorded as NW, which would be wrong. The wind vane also tends to freeze at one direction when it is below freezing.