Abstract: A rain water sensitive switch construction for use in connection with a lawn sprinkling system includes a pair of horizontally oriented perforated electrical contact plates spaced apart vertically to establish an air gap between the spaced apart contact plates, and a housing within which the contact plates are mounted above ground so that rain water passes into the housing and through the contact plates to bridge the gap and effect electrical contact between the contact plates immediately upon the onset of rain and is not retained between the plates so that electrical contact between the contact plates is discontinued immediately when the rain stops.