I have 2 snakes I paid for but are being held for shipping until the weather breaks. One of the snakes was something I had been looking for but of the 4 I looked at, only one seller was willing to hold it for a later ship date. To me, that is a responsible breeder and is part of the reason I went with his snake and not one the others. If a breeder either will not honor your request to hold the animal (with payment of course) for shipping OR will not give you an extended health guarantee (maybe a week due to the cold) then I would not purchase from them.
As a breeder, if you are concerned in any way about the weather then follow your instinct and tell the buyer you can not ship until the weather gets a little better.