Abstract: An Electrically operated valve controls the flow of irrigation water. A clock or computer controls the time of day and a programmed watering schedule. The clock signal is serially connected through differential relative humidity (RH) and temperature sensitive circuits. These circuits sense the difference between the surrounding RH and above ground temperature and set points derived from meterological “Normals, Means and Extremes” weather data. When the difference between the set point readings and the surrounding RH or temperature becomes zero and beyond, solenoid activation is prevented during and sometimes before inappropriate weather and evapotranspiration conditions; such as rain, snow or freeze.