This depends on many variables and is hard to accurately predict. The relationship between the rain sensor set point and how much it actually rains is the first variable. The longer it rains past the set point (up to one inch) the longer the system will stay off. Next, all the variables of the weather will determine how fast the water dries out: wind, sunlight and humidity all play a roll. In practice, all these variables usually result in the sensor shutting the system off a minimum of a few hours to a maximum of three - four days.