Sorry for the delayed response. I just saw this.

It is in the 20s here now and no problems. It was single digits a week ago and still ok. They have not frozen up on us at all.

The PetSafe company stands behind their product as well. I had a PetSafe collar that stopped working 11 1/2 months into the 12 month warranty. They sent me a new one without a lot of back and forth. Just an apology and a new one in the mail. What's not to love about that?! This is why I bought a Pet Safe door. I have a collar for the other dog and no problems at all with that one.

https://store.petsafe.net/extreme-weather-aluminum-pet-door#1076=1751

We got this door for our 2 labs and I am finally free from my second job as door person for the pups. The flaps snap shut very well, so it keeps the cold air out. We are in northern new york, near lake george so we get some cold weather. The dogs like it and so do we. It has a hard plastic cover to shut it for the evening.