More recent deposits are sand and silt sediments of the La Pine basin, overlain with sands and gravels deposited by glacial outwash from the Cascade Range. Soils derived from Mazama pumice and ash have only a thin weathered surface layer. Most of the soil profile is undeveloped, with low organic matter content, low nitrogen, sulfur, and phosphorus content, and high porosity. 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.