Preventing move outs during winter

[Jon Krueger]

I am currently working on a lease for  a new tenant in Buffalo, NY. The lease is month to month, but I would like to include that during the winter months they can not leave, as it is always harder to find new tenants during that time. Talking to a friend of mine he said that he has done this in the past and I just wanted to put this out there for a second opinion. Also, any suggestions on how to word this in the lease would be appreciated.