Senate Bill 17-245 took effect last Wednesday, August 9th.   The new law changes the notice requirement for terminating certain short term leases as well as raising rent.  Prior to the change,  landlords could terminate a month-to-month lease upon a written 7 days notice.  Under the new law,

landlords of a month-to-month lease are required to provide a 21 day notice for lease termination.  The new law also requires the month-to-month landlords to provide the tenant a 21 day notice before increasing the rent.  The law applies not just to month-to-month leases, but to leases between one month and six months.  Keep in mind the new law did not change the notice for tenancies that are less than a month.  Tenancies of one week or longer, but less than a month, still permit the landlord to terminate with a three day notice.