It's not impervious to cold. I'm willing to bet it can take more cold than I. Wouldn't be dumping the clutch on it before it's warmed up. In the FWIW column, I've ridden right at freezing and the belt wasn't a problem.

I went for a nice little ride today it has been in the low to mid 40s this afternoon. I put about almost 50 miles on it today. I have never heard my belt, but my front brake squeals a little bit when I pull it backwards, at least it did when I pulled it outside today. It may not do it now that I have rode it some.  I don't think I will be doing much more cold weather riding. I was wearing my insulated jacket, and lined gloves, and had a full face shield, but I was just wearing jeans, and my upper legs were pretty cold.  I would have been comfortable in coveralls. I have riding pants, but they don't fit well with the liner, plus I feel like I'm wearing a Power Ranger costume when I were them with the jacket.LOL

I recently discovered Axial Block gear.  I have the 1/2 zip and the pants.  The price is good (pants are about $40) and they do a good job.  The fit's a little odd since the windblock material doesn't allow them to stretch much, but I wear them under some fleece lined pants and my legs are just fine in the upper 20's and low 30's for my 45 minute commuting.
The thing about cold temp riding is allowing for all the extra time to gear up and change once I get to work.  And remembering to charge my new battery operated heated gloves.  Those are a life saver combined with handlebar muffs.

I've ridden this bike and a previous scooter in cold temps and never had belt problems.