Are winds that are not from the prevailing wind direction more often gusty, and why?
A little more info about where your airfield is would be helpful.

The generic answer would be that a significant weather event would be required to over come the prevailing winds.  Also, as winds changed from prevailing to cross, gusts and shears would be more likely.  Local low level factors such as terrain, buildings, and trees may also taken into account. The airspace along the runway is generally more clear of these effects as compared with across it for a single runway.  Larger airports with multiple runways provide more options.