Daytime to nighttime temperature variation within the soil profile can be extreme. The climate is continental, modified by proximity of the Cascade Range to the west and the Great Basin desert to the east. Most precipitation occurs as snowfall. Annual precipitation averages 24 inches on Pringle Butte and over 40 inches on Lookout Mountain. Daytime high temperatures in the summer range between 70 and 90 degrees.
Summer nights are cool and frosts can occur throughout the growing season.
Ecological site differences such as aspect and elevation, and past disturbance events, especially fires, insects, and disease, and more recent timber harvesting, have created a mosaic of rich biological diversity. Ponderosa pine is the dominant conifer through most of the experimental forest. Shrub layers include bitterbrush, ceanothus, greenleaf manzanita, golden chinkapin, and bearberry. A fire regime of low-intensity burns every 7 to 20 years, coupled with infrequent large and more intense fires, was common prior to the advent of modern fire suppression efforts. Dense lodgepole pine stands with bitterbrush, Idaho fescue, western needlegrass and bearberry occur on flats and basin bottoms that are slow to drain in the spring and, because of topography, are prone to frequent frosts that kill ponderosa pine seedlings.