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 lightning 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 the nights tend to be cold.
Winter storms can blow in suddenly with plummeting temperatures and rain or snow.
The weather in Big Bend, hot or cold, injures and kills more hikers than any other factor. Come well prepared because weather changes can be dramatic and unexpected. There is no kennel in or near the park. Rock is generally unstable in the park and may be dangerous. About two dozen mountain lions live in Big Bend National Park.