How I know it's Winter

I had to put on a light jacket and socks and boots. (new, brown, ankle, I have them in black as well. Very nice)

It was getting too dark at 4pm to wear my sunglasses. I came out of Sainsbury's and couldn't see with them on.

There is frost on the windows in the lounge. I think it's frost. Worryingly, it seems to be on the inside.

My toes are numb. Think I may need to wear slippers when at home.