I'll also go with skeeter on this. I dont open them until I need to. If your scope is fogging here is a tip to help prevent it....as a safe guard you could leave your rifle out side overnight so it is not subject to temperature changes. I put mine in the front seat of my truck overnight. Actually you shouldn't experience condensation forming when you go from warm to cold. Condesation usually forms when something is cold and then warmed. This is a golden rule for muzzleloaders. If you go out it in the morning and intend on returning for an evening hunt you should never bring the rifle indoors, condesation will form in the barrel and soak your powder charge.