Liable or apt to vary or change; (readily) susceptible or capable of variation; mutable, changeable… In miscellaneous applications.

Of weather, etc.: Changeable, variable.

Of the weather: changeable, unsettled; (of a period of time) having unsettled weather. Also of the wind, a breeze, etc.: brisk; gusty.

Having continuity or uniformity interrupted. of weather: Unsettled, uncertain.