Heat exhaustion
Signs: Heavy sweating, cool or pale clammy skin, weakness, dizziness, headache, nausea, muscle cramps.
Do this: Stop, get to shade, cool off, sip water with some salty food or electrolytes, and rest. Then turn back - don't push on.
Hiking / Trail safety
Heat & water - start here.
In Texas, smart beats strong - being fit won't save you from the sun. This is the section that matters most, so it leads: how to carry enough water, when to hike, and how to spot the heat emergency that kills. Then the other hazards.
The one to never miss
The one to never miss: heat stroke is life-threatening. If someone gets confused, slurs their words, acts strangely, has very hot skin, or passes out, treat it as heat stroke - call 911 and cool them fast (shade, water on the skin, fan them). If someone stops making sense, don't wait to 'see if it passes.'
Carry enough water
If you read only one section, read this. In Texas, smart beats strong - being fit won't save you from the sun.
- One gallon of water per person, per day is the minimum the National Park Service recommends in Texas's desert parks - and you need more while you're actually hiking. Going uphill in direct sun during the hottest part of the day, your body can lose more than two quarts of fluid an hour.
- Drink steadily and eat salty snacks. Water alone isn't enough on a long hot hike - you lose salt too, and drinking lots of plain water without food can cause a dangerous condition called hyponatremia (low blood sodium). Balance water with food.
Time it right
- In summer, hike early and be off the trail by noon. Afternoon is when the heat - and summer thunderstorms - turn dangerous. Save the long, exposed hikes for late fall through early spring.
- Many Texas trails have little shade. Wear a hat, sunscreen, and light, protective clothing, and don't count on finding a shady spot to rest.
Know the two heat emergencies
Heat illness comes in two stages - learn to tell them apart, because the second one is a 911 call.
Heat stroke (call 911)
Signs: Very hot skin, and - the key sign - confusion, slurred speech, acting strangely, or passing out.
Do this: Call 911 immediately. Cool the person fast: shade, water on the skin, fan them. Mental confusion is the red flag that turns heat exhaustion into a true emergency.
Two more habits that save lives
Watch the kids and dogs
If it's too hot for you, it's too hot for your kids and your dog. Kids overheat faster than adults and may not notice the warning signs. Dogs cool themselves only by panting and burn their paws on hot ground - a good test is your own hand: if the trail's too hot to hold your palm on for ten seconds, it's too hot for their feet.
Tell someone your plan
Cell service drops out in big parks like Big Bend, and it's easy to get disoriented in the heat. Before you go, tell someone where you'll hike and when you'll be back. Every year rangers rescue hikers who counted on strength alone - don't be one of them.
The other hazards
Heat is first, but keep these in mind too. For the deeper treatment of heat and flash floods, see the Weather hub.
Flash floods
In the Hill Country and the canyons, a dry creek or low-water crossing can fill in minutes - even from rain falling miles away under clear skies. Never walk or drive across moving water; it doesn't take much to sweep you off your feet. Turn around.
Snakes & critters
Watch where you put your feet and hands - around rocks, logs, and ledges. Most snakes are harmless and will avoid you (see the Wildlife hub for snakebite first aid). Use repellent for ticks, chiggers, and mosquitoes, and check yourself after.
Spiny everything
Cactus, mesquite thorns, and spiky plants are everywhere off-trail - one more reason to stay on the trail.
Getting lost
Big parks are vast and signs can be sparse. Download an offline map, carry the 'ten essentials' (map, water, food, first aid, light, and more), and don't count on cell service.
Lightning & storms
Summer afternoons bring fast thunderstorms, especially in the mountains. Get below exposed ridges and peaks before they hit.
Hunting seasons
On shared public land like national forests and wildlife management areas, hikers and hunters share the woods in season. Wear blaze orange - it's strongly encouraged on national forests and effectively required on WMAs - and check the area's rules (see the Hunting hub).
The border (Big Bend)
Big Bend runs along the Rio Grande and the Mexico line. The only legal crossing is the Boquillas Port of Entry - don't cross the river anywhere else. The backcountry is genuinely remote, with poorly marked trails and limited emergency help, so plan carefully.
More on these in the Weather hub (heat & flash floods), the Wildlife hub (snakebite), and the Hunting hub (shared land in season).
Keep going
Official sources
The heat, water, and hyponatremia guidance comes straight from the National Park Service's Big Bend 'Hike Smart' page and Guadalupe Mountains. For flash floods and the deeper hazard treatment, see the Weather hub.
- Data vintage:
- Trail safety as reviewed June 2026
- Last reviewed:
- June 15, 2026
- NPS Big Bend - Hike Smart - The heat & water guidance, straight from the source
- NPS Big Bend - top tips & safety
- NPS Guadalupe Mountains - hiking safety
- NPS - the Ten Essentials
Caution: Heat is the leading cause of trail rescues and deaths in Texas. Carry more water than you think you need, hike early, and turn back at the first sign of heat illness. When in doubt, don't go in the afternoon heat.
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