Maybe...maybe not.
Sudbury Ontario is pretty far north, so a cold snap could get pretty cold even in December.
Also, we don't know what model RV you have. Some have tanks largely enclosed and the furnace "wastes" some of the heat into the underbelly giving you a much lower risk of freezing. Others have the tanks fully exposed, so much easier to get freeze issues.
Then if you have access to electricity, there are heating pads and other options to mitigate, so it is possible.
In our last 5er, we were down to -5F for a couple of days. Lost the stinky slinky hose as it froze solid and I tore it trying to get it disconnected without waiting for it to melt...but otherwise no damage.
