The Virtual Rain Sensor is a device that activates or trips when it has rained or will rain. It does this by retrieving the past and future precipitation(rain, snow, sleet & hail) total for each day over a defined window of time then comparing the total to an adjustable threshold. When the threshold is exceeded the device will change state to "tripped" indicating that rain is detected. A free account with the Weather Underground API is required for this plugin to operate, but if you already have the weather plugin installed you can use that key. To get key...http://forum.micasaverde.com/index.php/topic,24538.0.html