Thursday 9am - 4pm. Hikers require one gallon per day per person. Start your return trip before half your water is gone. Treat spring water before drinking and don't drink the river water. Weather Annual precipitation is just under 10 inches in most of the park, but in wet years may exceed 30 inches in the mountains.
Summer brings hot days and warm nights.
Dramatic afternoon lighting storms with high winds are common and come on quickly. Heavy downpours may result in flash floods. Winter days may be sunny and warm, but nights tend to be cold. Winter storms can blow in suddenly with plummeting temperatures and rain or snow. Come well prepared because weather changes can be dramatic and unexpected.