The Big Bend Heat & Hydration Safety Guide, Written by a Nurse Who Lives Here

You'll feel fine at the trailhead. That's the part nobody warns you about. You'll step out of the truck at Big Bend, the sky will be enormous, the air will be dry and light, and your body will tell you everything is great. Meanwhile the desert has already started taking water out of you, and it will keep taking it, quietly, for hours before you feel a thing.

I'm Polli. I've been a licensed nurse for 35 years, 15 of them in a neonatal ICU, and I live in Terlingua, right outside the park. Every summer I watch good, healthy people get caught by heat they never felt coming. Big Bend runs somewhere around 40 search and rescue incidents a year, and a lot of them trace back to the same quiet thing, dehydration that got a head start. So before your trip, let me give you the nurse version of a kindness.

Why the heat out here is sneaky

In Houston or Dallas, sweat sits on your skin and you feel wet and miserable, and that misery is useful information. Out here the humidity is so low that sweat evaporates the instant it forms. You never feel soaked, so your brain never sounds the alarm, and you can lose a shocking amount of water while feeling dry and pleasant. Add elevation, sun with no shade, and the excitement of a trip you drove eight hours for, and people push right past the point they'd normally stop.

Thirst is a late signal in the desert. By the time you're thirsty, you're already behind.

Start hydrating the day before

Pre-hydrate. It's the single best thing you can do, and almost nobody does it. Starting the day before your first hike, drink steadily, with meals and between them, until your urine runs pale yellow. Skip the second margarita the night before a big trail day, or at least match it with water, because alcohol pulls fluid out of you and the desert will happily finish the job.

Coffee is fine in the morning. Just don't let it be the only thing in your cup before you walk.

Water alone is not the whole answer

When you sweat, you lose sodium, potassium, and magnesium along with the water. Drink plain water all day without replacing those and you can end up feeling worse, headachy and weak and off, even with a full bottle. So bring electrolytes. Powders, tablets, or the sports drink you like, it doesn't much matter which. Salty snacks on the trail count too. Alternate, water then electrolytes, all day long.

How much to carry

More than you think. My rule for summer out here is about a liter for every hour you plan to be moving, and a full gallon per person per day at minimum. Then put an extra gallon in the car that you never plan to touch. Most trails in the park have no water at all, and there is nowhere to refill once you're out there. If you turn around with water left over, you did it right. Nobody has ever regretted carrying too much.

Time your hike like the locals do

From May through September, the desert floor can top 110 degrees by early afternoon. So be on the trail at first light and plan to be done by 10 or 11 in the morning. Save the low, exposed hikes for winter and pick shadier, higher ground like the Chisos Basin in summer. Wear long light sleeves, sunscreen, and yes, wear the hat! Rest in shade before you feel like you need it, and turn around earlier than your pride wants to.

Know the line between rough and dangerous

Feeling wiped out, headachy, a little nauseated, and heavy-legged after a hot hike, that's your body telling you it's behind on fluids. Get to shade and air conditioning, sip water with electrolytes, and rest.

Confusion, stumbling, slurred speech, skin that's hot and dry when sweating stops, fainting, or vomiting that won't quit are different. Those can point to heat stroke, and heat stroke is a medical emergency. That is a 911 call or a drive to Big Bend Regional Medical Center in Alpine, immediately, no waiting to see if it passes. I say this as a nurse who loves this place. When it's severe, the ER is the only right answer. Check your symptoms here trailcheck.desertelixirs.net

And if the desert gets ahead of you anyway

For the ordinary kind of worn down, the dragging-back-to-the-truck, can't-face-dinner kind, that's what I do all day out here. Desert Elixirs is my little IV hydration clinic in Terlingua, licensed nurses, by appointment, 7 days a week. Our Rehydration Mix is $200, built for heat-stunned hikers who need fluids back in them, and most guests tell me they feel like themselves again within the hour. Real talk, if you can't keep anything down at all, that's not me, that's the ER I just told you about. Otherwise, stop by the clinic on your way out of the park, or I'll come to you, your rental, hotel, or campsite, for a $50 fee within 30 miles. If you're not sure what you need, a consultation with our nurse practitioner is free, no obligation at all.

Drink early, carry extra, beat the sun, and go have the trip you drove all this way for. And if the heat catches you anyway, no worries. We've got you.