Lightning. Thunderstorms, hail, and lightning are very common, especially in the late afternoon at high altitudes. If possible, get below timberline if you see a storm approaching.
Fires and floods. Be aware of the possibility of forest fires and flash floods. Fires can move quickly, so watch for the smoke when you are at higher elevation. At certain times of the year, fire danger can be extremely high and the Forest Service will post-fire danger warnings. During these times, campfires may be prohibited. Heavy rainstorms can cause flash floods at any time during the spring and summer. The danger is particularly acute if you are in a narrow canyon. If you have reason to believe a flash flood is imminent, do not try to outrun it. Abandon your vehicle and climb to higher ground.
Altitude sickness. Some people experience nausea, dizziness, headaches or weakness the first time at high altitude. This condition usually improves over time. To minimize symptoms, give yourself time to acclimate, drink plenty of fluids, decrease salt intake, reduce alcohol and caffeine, eat foods high in carbohydrates, and try not to exert yourself. If symptoms become severe, the only sure remedy is to return to a lower altitude.
Hypothermia. Hypothermia is possible even in the summer. If you get caught in a sudden shower at high altitude, your body temperature can drop suddenly. Always take rain gear and warm clothing.
Don’t drink from streams. No matter how cool, clear or refreshing a mountain stream may appear, never drink the water without boiling it, using a filter or iodine tablets. Best to carry your own water.
