As mentioned, a little more info ( model motor etc) would help but the general rule is to have the motor tilted down, in or out of the water in freezing temps. More importantly, if you have a fresh water tank, livewells or bilges that usually get water from rain, melting snow etc. you may have a risk of freezing. Fresh water tanks should be drained, then treated with RV type antifreeze and that solution run for a bit through the plumbing. You may want to disconnect hoses and drain/blow out standing water.
Note that anything stored on the boat that can freeze , will freeze if it gets cold enough.