It's just cold

Plain ol' cold.
This is a flower pot that used to contain our bell pepper plant. The plant died because of too much rain, so we tossed it into the woods out back. The empty pot got filled with rain water. Shorter days. Less sunshine. And, well, the pot remained full of water. Full of water, that is, until the weeks on end of freezing or below freezing temperatures.

Now, the pot is just full of ice.
Yeah, it's just cold.