“When do I turn the water on?” “How long should I leave it on?”  WSU researcher, Dr. Troy Peters, developed a mobile app to help you answer those questions on your smart phone based on local weather data.” 

https://play.google.com/store/apps/details?id=com.sandyclock.irrigation   (Android App)

https://itunes.apple.com/us/app/id1052353432  (iPhone App)