This will also prevent moisture from condensing on your instrument. Low humidity in winter is not usually an issue for banjos unless your banjo has a skin head. If this is the case, you will need to keep your instrument in a humidified environment or possibly loosen the head slightly. A good quality skin head is less likely to split due to dryness. Traveling can pose a few hazards.
Instruments are safer in a hard shell case, but remember to guard against heat damage.
Also, airlines are notorious for damaging instruments. You may not be allowed to carry your instrument on board, and your instrument is often treated no better than someone's socks and t-shirts. Think twice before deciding to fly with your instrument. Consider shipping it instead. Mystery Damage Be aware that your instrument can be damaged while it is in the case, even a hard shell case.