This steam sensor can be connected to the Arduino IO Expansion shield directly and also XBEE module,Arduino Shield V5.0 to detection it is rain or not. The sensor can placed outdoors, when the rain dripping on the detection surface, the output voltage will increase when the humidity of the sensor surface goes up. Arduino UNO will know it is rained, coupled with a MP3 module, you could achieve Music Notifications. In addition to detecting the rain, the fog and moisture also can be detected.
Note:The connector is not waterproof, please be careful not to put the connector directly in water.