I ride unless it's under 15*, if it's under 30* he gets a quarter sheet and majority is spent just walking and doing circles and other bending work. I do have an indoor available to me though. Outside I'll ride so long as it's not icy. Deep snow is just shorter rides as it's a lot of work, but a fantastic hind end workout. But will stop after 15/20 mins. Frozen ground will again just be a walking workout or will do ground work.