Extensions to Rain Alarm:

• No advertisement
• Customizable settings
  • Update interval, search radius
  • Automatic location update interval, manual location, GPS, network location
  • Animation interval, animation rate, map transparency
  • More widget themes
• Customizable alarms
  • settings for time frame, distance, intensity, area, sound (including speech output), vibration, notification
• Sony SmartWatch used for notifications, widget and app

One option is to buy and download the app through Google Play:

Download Rain Alarm Pro from Google Play

Download Rain Alarm OSM Pro from Google Play

An alternative option is the App Center of AndroidPIT. You are able to pay there also by PayPal.
Download Rain Alarm Pro from AndroidPIT
Download Rain Alarm OSM Pro from AndroidPIT