Should I have believed the frost warning? Yes. It was two degrees above freezing when I walked and one degree above when I ate breakfast. I assumed we had not reached the magic number, even though the pasture was suspiciously white. An hour or so later there was water dripping off the deck railing. I went out to touch it to see if frost had formed there. With direct sun on it, there was only water. My eyes slid over several inches. Golly Pete! There was ice on the birdbath!
The solar pump was not working, and I thought it was broken, clogged by ice. I gently pulled it out, where it left a hole in the ice. Ice made a circular frame for a green and brown leaf under it. The ice was at least ¼ inch thick, more than enough to make a skating pond for the birds. The fountain did work, and I put it back so the birds could see there was running water for them.