There are certainly disadvantages to going to Niagara in January. The main one is freezing to death. It was so cold when we turned up, the falls were partially frozen. (It’s the fault of my job. I travel. But always in the off-season.)
Visit in January, however, and you can do everything in about an hour flat that it would probably take you the whole day to do in balmier temperatures. When you go through the tunnels behind the falls, you will pass by whole rooms that are reserved for queues in the summer. Stand against the backdrop of icicles, and you will be alone.
Another advantage of visiting in January is that you’ll be practically the only tourists there. Our pictures are noteworthy for the lack of any one else in them. As we arrived, early on a Sunday morning, startled shopkeepers hurriedly flipped their signs to “Open”. No queues there, either.
Which means you also won’t have to wait if you feel a sudden need to buy a warm hat.
Which you probably will.