How do you stay safe hiking in the heat?
Start at dawn, carry plenty of water plus salty snacks, and choose shaded or shorter trails when it is hot. Turn around early if you are running low on water or feel dizzy, sick or weak. Heat stroke causes confusion and can happen far from help, so leave a trip plan and set a return time. Holler alerts your Guardians if you do not check in after it.
Planning a hot-weather hike
01Choose the trail for the temperature
Exposed ridges, desert washes and south-facing slopes can be brutal by late morning. The National Weather Service says full sun can raise the heat index by up to 15°F, which is why an open ridge feels so much hotter than a wooded valley at the same air temperature. On hot days, pick forested trails, routes along water, or higher elevations. Canyons invert the usual pattern: the easy downhill comes first and the hard, hot climb comes last.
02Carry more water than the map suggests
Streams on the map may be dry, and water sources need treating. Carry what you need for the full hike, plus a reserve. Eat salty snacks along the way so you replace what you sweat out.
03Set a turnaround rule before you start
Decide in advance to turn back when half your water is gone or at a set time, whichever comes first. It is easy to push on toward a summit in the heat and then face the whole return with empty bottles. Check your urine at breaks too: the CDC says light yellow or clear usually means you are drinking enough, so dark and scant is a reason to head down.
04Know the signs of heat illness
Heavy sweating, headache, nausea, dizziness and weakness are heat exhaustion signs in CDC guidance; rest in shade, loosen your pack and clothing, sip water and wet your head and neck. Confusion, slurred speech, seizures or hot skin mean heat stroke. Call 911 if you have signal, then start cooling with whatever water you carry: soak their shirt and hat and keep them in shade. The National Weather Service advises not giving fluids to someone with heat stroke. On a remote trail help takes time, so cooling cannot wait.
05Leave a plan and a return time
Tell someone the trail and when you will be out, and set a return time in Holler. If you miss it by five minutes, your Guardians get an overdue alert with your last location, even with the app closed. Holler cannot sense heat illness, so this check-in is the safety net. Our guide to leaving a trip plan walks through it.
Related questions
What time should I start a summer hike?
As early as you safely can, ideally so you finish before the hottest part of the afternoon. Use a headlamp for the first hour if needed. Our daylight tool shows sunrise and sunset for planning.
What if I lose signal on a hot trail?
Updates to your live link pause without signal, but your Guardians still see the last known location. A return time still works because Holler's server tracks it, so the overdue alert goes out even if your phone is out of range.
Is drinking a lot of water always safe?
Drinking huge amounts of plain water without eating or replacing salt can cause problems on long, hot hikes. Balance water with food and electrolytes. If you have a heart or kidney condition, ask your doctor about fluids.
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Sources, checked September 2026: CDC NIOSH: Heat-related illnesses, CDC: About heat and your health, National Weather Service: Heat exhaustion and heat stroke, National Weather Service: Heat index and heat forecast tools.
More safety answers, or see the safety guides.