Atmospheric conditions have some direct and indirect effects on plant growth in many ways. This effect is important especially in physical, chemical or biological process in plant growth. Deviations from optimum conditions could negatively affect plant growth. Thought that the climate is the main factor limiting the plant distribution and living, the climatic parameters would be used as indicators of plant productivity. Annual mean temperature (TEMP) and annual mean precipitation (PREC) are two of the most used climate factors to model stand productivity. Annual mean minimum-maximum temperature, temperature and precipitation in growing season, actual evapotranspiration (AET) and moisture index have been also used in related studies. This study aims to determine the relationships between some climate factors and the site index (SI) of oriental spruce (Picea orientalis (L.) Link.) naturally distributed in Rize-Kackar Mountainous Ecoregion in Turkey. Within this scope, 54 sample plots were visited in the study area and tree height, tree diameter at breast height and stand age were measured in each sample plot to determine SI. Climatic data was obtained from meteorological stations closest to study areas Results showed that SI of oriental spruce were positively correlated with annual mean temperature (r= 0,424), mean temperature in during season (VTEMP) (r= 0,484) and annual AET (r= 0,312). On the other hand annual mean precipitation (r= -0,593), mean precipitation during growing season (VPREC) (r= -0,633) and the Thornthwaite moisture index (THMI) (r= 0,541) were negatively correlated with SI. To model the SI multiple linear regression technique was used. The model, consisting of VTEMP and VPREC accounted for only 42,7 % of the variation in SI. The results show the importance of climate factors on oriental spruce growth, especially in site selection for afforestation activities.