We get this question a lot since our original shipping location was in Arizona. No worries; we checked with our biochemist at the lab and although prolonged heat exposure for several days over 150 degrees is not good for stability,, the heat should not make a difference as we ship priority mail in 1-4 days. Shipment now originate from TyH's Maine. location. If you have an outside mailbox, it's a good idea to check your tracking number once your package has shipped so you will collect it timely in any extreme hot or cold weather, though.