 Harrison County is in the humid subtropical climate region of the United States along with most of Southern Indiana . Its Köppen climate classification is Dfa , meaning that it is cold , has no dry season , and has a hot summer . However , it is close to the southern edge of this region . In recent years , average temperatures in Corydon have ranged from a low of 21 ° F ( − 6 ° C ) in January to a high of 88 ° F ( 31 ° C ) in July , although a record low of − 31 ° F ( − 35 ° C ) was recorded in January 1977 and a record high of 104 ° F ( 40 ° C ) was recorded in July 1983 . Average monthly precipitation ranged from 3 @.@ 13 inches ( 80 mm ) in October to 5 @.@ 06 inches ( 129 mm ) in May . 
