I store my guitar woods and finished instruments in an environment that is between 40% and 50% relative humidity. I also prefer to store my freshly cut, or delivered guitar woods in this environment for a period of time before construction begins. This ensures that the instrument will be stable once it is put together. Once completed, the instrument needs to be continued to be stored in this environment. Many homes in the Midwest have widely varying humidity levels in the winter, (very dry). This can cause sharp fret ends from shrinking fretboards, checks or cracks in the guitar, or loose braces. Because of this I supply every Czeiszperger Guitar with a case humidifier. I recommend that you store your guitar in the case and regularly monitor humidity levels.
Storing a guitar in a very hot environment, like the trunk of a car on a hot day, is also a recipe for disaster and will void the warranty. Czeiszperger guitars are built far more lightly than some of the tank guitars being sold today. The must be carefully treated like the heirloom instruments that they are.