if you have a heater, that'll be the first thing to have damage and it won't take much of a freeze to do it, after that you need something long and colder to hurt the engine.
In SE wisconsin we leave ours on the lift until it starts dropping to right around freezing at night, then pull it into the garage where it will stay a few more weeks until it starts hanging out below freezing for the whole night instead of a few minutes. If it is on a lift, the water will help keep it warmer, you'll notice that on the ground with frost too...the frost usually won't get as close to the lake until it's colder for longer periods because the lake is a warmer body.
Typically, we pull on Halloween for the last time and winterize the last boat. Sometimes earlier and sometimes later. having gone to college in Minnesota, I'm well aware it gets colder sooner, you maybe done any day now