The Snake River and Jackson Lake are dominant components of the valley floor. Maximum size of Jackson Lake is 10,292 ha.
Summers are cool and short, while winters are cold.
Annual precipitation is approximately 61 cm. Three fourths of this precipitation is accumulated in a mean annual snowfall of 405 cm. Upland vegetative communities are complex and varied. Lodgepole pine predominates in the dominant coniferous forest community, while sagebrush dominates the shrub community. Willow, narrow-leaved cottonwood, and blue spruce dominate the riparian communities.