Depends on the weather but your butt against the padded seat for long periods of time is usually enough to keep it warm. If you want a toasty bum you're gonna need a heated seat.
Ontario Canada eh? I guess you would know. On the other hand, did you know that a heated seat might cause temporary sterility? Yep, have to keep those baby makers below body temperature or they will fry. Just a word of caution.