Avoid strenuous activities during the day. Desert thunderstorms carry the double threat of flash floods and lightning. They occur most often in summer and fall. Be wary of nearby storms.
Violent downpours can cause flash flooding in distant areas untouched by rain.
Never camp in a wash or other low-lying area or drive across a flooded road. Stay out of open areas where lighting may strike. Weather information is posted daily at ranger stations. Wear sturdy boots and watch where you step. A microscopic amoeba, Naegleria fowleri , which can live in hot springs, can cause a rare infection and sometimes death.