I suspect you may be smoking outside. If so this is a common occurrence this time of year. You will find many similar posts. When moving from a warm inside storage to a cold smoking area this often results in a cracking wrapper. Sometimes you may find that your cigar may even seem to "explode" as the filler/binder expand in the cold.
How to prevent this occurring? I dont know as I live in a relatively warm house and smoke inside, sorry.