Degree-days are fundamental design parameters in many application fields such as power generation and consumption, agriculture, architecture, snow melt estimation, environmental energy planning, population siting, and military domains. Depending on temperature fluctuations, the degree-day statistics at any location show local and seasonal variations. Among these parameters the average degree-day durations for cooling and heating periods, degree-day sums, and their maximums play a significant role in practical applications. In the body of literature to date the average degree-day durations have been analytically studied most often for independent processes. In this paper, however, degree-day sums in addition to durations are considered as important design variables with analytical formulation for dependent processes on the basis of the first-order Markov process. The application of the methodologies developed are presented for five temperature measurement stations scattered throughout Turkey within different climate regions.