I did a quick search and found a few places that have year-round campground/RV facilities in the Niagara area. I was actually surprised by that a little bit. The weather is starting to improve "up north" but is, as mentioned, unpredictable this far ahead. Still, I'd wager the worst of it is over - at least, I'm hoping it is because I'd like to see a color other than white outside - and you should be okay with your plans. There certainly can be those freak, late-season storms, but I wouldn't let that stop you from pursuing your trip, as long as you can be flexible and able to change plans to accommodate such an event should it occur.

Watching ice getting thrown over the Falls would be a bit of a guilty pleasure I'd think. Seeing the last vestiges of winter getting pummeled might provide a small bit of satisfaction and a knowing grin that spring was soon to arrive!