When I got to the barn it was 37 degrees with a nasty icy drizzle. I trotted from the parking lot to Nina's pen, checked to make sure she was warm and dry, dumped her lunch in her feed bucket, trotted back to the car and zoomed home. brrrrrrr
I used to ride when it was really cold, down in the teens. Colder than that is hard on the horses although I have gotten on and just walked around at temps near zero. Then I decided that 32 was a nice number. No riding below 32 degrees. This year I am thinking that 40 sounds good.
My hat's off to the Brits, who apparently ride in this wet crap all the time. I am holding out for either warmer or drier.