This applet will send you a text when it starts to rain.
If
Current condition changes to
This Trigger monitors changes in the current weather condition. When one of those conditions is met the Trigger fires. Currently only these simple conditions are supported: Rain, Snow, Cloudy, Clear.
Then
Send an SMS
This Action will send an SMS from your Android device to any phone number you specify.
Discover more time saving integrations for Android SMS and Weather Underground