The climate of the basin is moderate with temperatures averaging about 60 degrees Fahrenheit, and rarely exceeds 100 degrees Fahrenheit, or falling below zero. The length of the average growing season is about 210 days, extending from early April to the end of October. Annual precipitation for the basin averages 47 inches. For the most part, soils along the shoreline are thin and rocky and large sections of exposed bedrock are common. Forests in the area have been repeatedly cut and are compromised mostly of oak, hickory, and eastern red cedar.
Cedar glades are common throughout the area, and contain several rare and endangered plants.
The overall water quality of J. Percy Priest is good, although there are times during the year when dissolved oxygen conditions decline. As the lake becomes older and richer in nutrients, the ability of the water to maintain the dissolved oxygen content declines. This enriching process is a normal occurrence which is caused by the decay of aquatic plants and animals, but is accelerated by runoff from farming operations and sewage associated with lake use and adjacent property owners. The reservoir is thermally stratified for about 7-8 months of the year and anaerobic conditions in the hypolimnion exist for at least five of these months. During the period when the hypolimnion is anaerobic, the concentrations of ammonia, phosphorus, hydrogen sulfide, iron and manganese increase significantly in the deep layers.