Are you sure? In the manual they say that “The sensor is for indoor use only and can be used in temperatures ranging from 0ºC to 45ºC.”
Meanwhile, Customer Service says that it can be used outdoors…
Still going strong since August. It has been wet since.
There’s also this. But if the battery runs out after the claimed 10 year battery life you need a new one, and I’m not sure about compatibility: