What sort of workouts do you do in the winter that might be different from your workouts during the other seasons?
Shovelling snow is a surprisingly effective workout, not one I tend to do very often in the summertime
Hiking isn't as readily available in the winter, although I'm looking into getting some winter-friendly clothing so I can still do at least some walking done even if I stick to the mountain roads rather than the trails. Where trails are steep and rocky I can see them being treacherous in the snow.
An indoor bicycle is boring as far as exercise goes but works much better in the winter than the summer. When it's a struggle to keep the place cool the last thing you need is a workout that makes you sweat a lot but without moving the air over you to help cool and evaporate the sweat.