New York City landlords must turn on heat systems beginning October 1st. The heating systems must be kept on though May 31st and meet minimum temperature requirements.
During the day, between 6 A.M. and 10 P.M, if it is below 55 degrees outside it must be at least 68 degrees inside. At night, between 10 P.M. and 6 A.M, if it is below 40 degrees outside, it must be at least 55 degrees inside. These requirements only apply to buildings in which the landlord controls the heat. The temperature is the responsibility of the tenants in buildings with individual heating systems in each unit.