Putnam County experiences a temperate climate with generally mild winters and moderately humid summers. Cold weather comes mostly from the northwest, originating in western Canada, while heat and humidity come from Gulf-coast air masses. Prevailing winds during the summer months are from the southwest; prevailing winds in the winter are from the northwest.
Putnam County is near the border of North American Agricultural Zones 5 and 6. The Zone 6 hardiness band, in which Greencastle is located, is hardy for most common North American fruit, shrubs, and ornamentals. The growing season is 175 days.
Minimum Average: 17°F in January
Maximum Average: 84°F in July
Average Annual: 45.53 inches / 115.6 cm
Average Annual: 23.0 inches / 58.4 cm
Cooling Degree Days
Annual (65°F Base): 804
Heating Degree Days
Annual (65°F Base): 5,938
Percentage of Available Sunshine
January & December: Approx. 40%
June, July, August & September: Approx. 70%
Data based on Weather Station ID: 123513 – Greencastle 3 SW.
30 Year Normals – 1981 to 2010. The next update of 30 Year Normals will be 1991 to 2020.
Indiana State Climate Office at Purdue University