Winter is a hazardous time for guitar and bass finishes – if your instrument lives anywhere that the temperature varies substantially, and your instrument is subjected to those changes – such as when being transported in a cold vehicle on the way to a warm gig – then it is in danger of checking. Fortunately, modern finishes are much more durable than those of years past, but checking can still be a problem.
To prevent checking (a.k.a. weather checking) or cracking, allow the instrument to acclimate to the temperature of its environment very slowly. This means leaving it in its unopened case for as long as possible after bringing it into a warm room from the cold. It may take as long as a few hours for the instrument to completely warm up – avoid the temptation to open the case to “check” on it!