Contact lenses should not be stored in anything other than contact solution, and should be cleaned every time you take them out. You can soak them in the solution for days on end and they'll be fine. Once you take them out, though, just rinse them in clean solution. Don't completely soak the contacts in solution- that's a waste of money! Just cover the lenses enough so that they don't stick out. Also, store your case in an area that's room temperature because other temperatures affect the lenses like you thought. The cold makes the contacts more rigid, and the heat makes them looser and flatter.