Storing your data copies is just as important as making them. All media have a range of temperatures that they can safely survive. Long term storage in high humidity can also affect many backup media choices. Pick a place for your data storage out of the light, heat, extreme cold, and of moderate humidity. Test your backups periodically and use fresh media on a scheduled basis to insure the highest possible integrity for your backups.
Don't keep your backups in your car. To convince yourself of this, put a cassette tape and a CD on the dashboard of your car and leave it there all day in August. Perform this test only on material that you consider trash in the first place.