The Kozara National Park belongs to moderate climate zone, with clearly marked four seasons. Continental influences are expressed in the north-eastern part of the National Park.
Climatic conditions are characterized by:
-Summer: Average temperature in July at the foothills of Kozara Mountain is 210 C. With the increase of altitude, the temperature decreases, so isomers of 500 m have about 200 C.
- Winter: It could be said that the area of Kozara Mountain below 500 m, has less than 30 snow days. Most part of the Kozara Mountains lays above 500 m of height and has 30 to 40 snow days, and the highest part of it has 40 snow days.
The average annual rainfall in the northern part of the National Park is 900 to 1000 mm, in the southern part it is 1000 to 1250 mm, and in the vegetation period (IV-IX) from 500 to 600 mm on average for the whole area.