Thornthwaite climate classification indices are essential to interpret climate types in Bartin City, simplifying calculation process and interpretation of climatological water balance by forests. Thus, we aimed to develop a climatological water balance by the Thornthwaite method, as well as climatic characterization using the indices proposed by Thornthwaite for Bartin (including measurement points are Amasra, Arit, Hasankadi, Kozcagiz, Kurucasile, Ulus, Ulus Cubukeli, Ulus Ceyupler Koyu). We used historical series of climate data from all 15 metrological stations of Bartin between 1988 and 2019, which were divided into measurements regions. Air temperature and precipitation were collected on a daily scale. Precipitation and potential evapotranspiration data allowed calculating water balance by the Thornthwaite method. We characterized all locations as wet and dry using aridity indices proposed by Thornthwaite. Maps were generated from climate indices of Bartin using kriging interpolation method with spherical model, one neighbor, and 0.25° resolution. The measurement regions showed different patterns regarding water balance components and humidity index. Humidity index had a mean of 16.97. The prevailing climate in Bartin is moist subhumid. Bartin has two well-defined periods during the year: a dry and a rainy period. Three climate types predominate in Bartin and, according to the Thornthwaite classification, are humid, moist subhumid, and dry subhumid. Water characterization in Bartin showed 123.67 mm year−1 of water surplus, 79.7 mm year−1 of water deficit, and 1003.9 mm year−1 of potential evapotranspiration. Water deficit and potential evapotranspiration decrease as latitude increases.