A temperature switch (or other “normally open” sensor switch) can be connected to sensor terminals of controller. When sensor contacts close, a watering cycle is initiated in program #6. The cycle will continously repeat as long as the sensor switch remains closed. If the Frost Override Option (one of 16 programmable options) is used, programs 1 through 5 will be suspended during the sensor activated operation of program #6. When the sensor switch opens, the watering cycle in program #6 will immediately stop and programs 1 thorugh 5 will be allowed to resume operation.