Whenever its cold out at night, I get a ton of ice inside my rear windows. I have a wrx wagon. Has anyone experienced this? Does anyone have a solution? This has been going on for about a month now, and its beginning to get very irritating.

please help...

The ice is condensation which is freezing on the windows.

It's easy to explain - you get in the car with snow or water on your shoes - this melts when it warms up and then evaporates as the carpets/mats dry. You hop out and go inside, the moisture which is now in the air in your car condenses on the coldest surface it meets - your car windows, then as the temp drops through the night the condesation freezes.

Clean as much snow/ice/water off your boots before you hop in the car.