Buddy of mine clocked 50 day seasons at Whistler while doing dentistry @ UBC (Vancouver). First two years of med you will be able to ski a lot if you sacrifice other things (mostly on weekends, you absolutely cannot skip lectures, at least at the schools in Canada). Third year probably less because you are busy for 12 months with clinical rotations (although if you stack them properly you can get 4 weeks off consecutively @ Christmas). 4th year you will probably get more days than 3rd year. Residency you will not be skiing much.
After residency it depends on what you are doing, you can design your career to have flexibility e.g.:
Dentists - can ski a ton, work a week on/week off and still make $200k, or work 4 days a week. If you have your own practice it will take a while to build up to this.
Emergency - 8 hour shifts, can stack them 4 on/4 off
Family Medicene - very flexible
Surgeon - maybe not
It just depends how much you want to work, how much money you want and where you live.
Also there is no such thing as pre-med, it just sounds stupid and pretentious. You do your BSc with pre-reqs and hopefully get good enough grades and life experience to get into MD.