Heat is rarely an issue for woods and guitars. Cold can be a problem but only when it's below zero. The only time we recommend delaying opening your package is if your guitar arrives in subzero temperatures. If this happens, we recommend leaving your package in your living room for 2 hours, then opening it. This allows the woods and fresh finish to acclimate to the indoor temperature. Rest assured we insure our packages twice, personally and also through FedEx, so if anything happens to your guitar we simply send you a brand new one.