Don't take chances - altitude sickness can cause serious illness or even death. The visitor needs to be prepared for rain or snow, and have protection from the sun. Also be prepared for cold nights. Layered clothing is best. Always carry water, sun lotion, a hat and dark glasses are necessary due to the greater exposure to ultraviolet radiation.
Thunderstorms are potentially dangerous.
Avoid exposed areas. If you are caught in the open, get away from metal objects including metal pots, pack frames and tentpoles. Sit on your pack or something insulated since the current will travel in granite. Avoid standing near large rocks or under large, solitary trees. Consider descending to a lower elevation.