Summer days can be warm at lower elevations, temperatures at higher elevations will be much cooler. Night time temperatures often drop to freezing or below even in summer. Afternoon and evening thunderstorms are common. Snow can occur anytime of the year, especially in late spring and early fall. Raingear, good boots, and warm clothes are essential.
Stream flows can be high and swift during snowmelt runoff periods and during periods of heavy rain.
Do not underestimate the power of rushing water. When fording a stream unbuckle your pack waist strap, and use a long stick for stability. The California Bighorn Sheep Zoological Area is located within the John Muir Wilderness, was established by the Inyo National Forest to minimize human disturbance in key sheep areas. Please contact the Mt. Whitney Ranger Station concerning these restrictions. Before going, check with the local Ranger Station for the latest weather conditions and possible hazards, such as swollen creeks and snow.