Ours is never frozen.  I think the purpose of the cooler is to keep it from getting too hot - or from freezing.  It can get pretty warm/hot here in Virginia from springtime through fall.  In the winter we can get cold too - just depends - we have been having some pretty cold weather Nov and Dec and part of Jan.  They used to send it to me in a padded envelope and leave it in the mailbox until I questioned it (after about a year) when I realized it should not be exposed to extreme heat!