I do leave my Wichita out all year. I have the Yoder cover for it, which to be honest isn't as helpful as I was hoping it would be. The current material faded badly and provides minimal water protection. (see picture)
I know they recently updated some things regarding the cover, and hope it's a better material and fit than it was previously, but I don't know. I wouldn't want mine to get snowed on all year, but don't have room in the garage and don't want to put ruts in my yard moving the beast back and forth! I've smoked in subzero temps with good results (I think it was about -5 when I took this pic, I had the pit uncovered the night before so it'd be quick to roll out of bed and start the fire, hence the frost), so I'd say get a cover and make it a year round thing!
- cold morning