What is the biggest danger hiking around St. George?

Heat, by a wide margin, followed by flash flooding in slot canyons. Heat problems typically develop on the return leg, when you are tired, low on water and further from the car than you realised — which is why the rule is to turn around on time rather than on distance. From June into September, hiking here means starting at first light and being finished by mid-morning, which is what residents actually do rather than an abundance of caution.

How much water should I carry?

Considerably more than you would for the same distance in a cooler climate, because dry air removes fluid without obvious sweating and you dehydrate faster than the discomfort suggests. Drink before you feel thirsty, and remember that heavy sweating loses salts as well as water, so replacing water alone on a long hot day creates its own problem. Never plan on finding water — desert sources are unreliable and seasonal.

How do I know if a slot canyon is safe to enter?

Check the forecast and any flash-flood outlook on the day, and do not enter on an uncertain one. The critical point is that the danger comes from rain you cannot see: water arrives from storms miles upstream while the sky above you is clear, so 'it looks fine' is not an assessment. If water rises or turns muddy, or you hear a roar, get to high ground immediately rather than heading downstream.

Desert Hiking Safety: Heat, Water, and Flash Floods

Desert hiking safety in southern Utah: heat, water, flash floods, snakes and the mistakes that actually put people in trouble.

Southern Utah is a forgiving place to walk in March and an unforgiving one in July. Almost every incident here traces to the same handful of misjudgements, and all of them are avoidable.

Heat is the thing that hurts people

Walk at the ends of the day. From June into September, the middle of the day is not hiking time. Locals start at first light and finish by mid-morning. This is not caution — it is how the season is survived.

Turn around on time, not on distance. Heat exhaustion arrives on the return leg, when you are tired, out of water and further from the car than you think. Decide your turnaround time before you start and keep it.

Know the signs. Headache, nausea, dizziness, cramps and stopping sweating are all warnings. Get into shade, cool down and drink. Confusion or a lack of sweat in heat is an emergency, not a rest stop.

Water: more than you think, and not only water

The dry air here removes fluid without obvious sweating, so you dehydrate faster than the discomfort suggests.

Carry considerably more than you would for the same distance in a cooler climate, drink before you are thirsty, and remember that heavy sweating loses salts as well as water — replacing water alone on a long hot day is its own problem.

Never plan on finding water. Desert sources are unreliable, seasonal, and frequently not what a map implies.

Flash floods kill people in slot canyons

This is the hazard visitors most consistently underestimate.

Rain far away is the danger. Water arrives from storms you cannot see, into a canyon where the sky above you is clear. That is the entire mechanism, and it is why "it looks fine" is not an assessment.

Check the forecast and any flash-flood outlook on the day.
Do not enter a slot, wash or narrow canyon on an uncertain forecast. Late summer is the season of concern.
A dry wash is not a path. It is a drain.
If water rises or turns muddy, or you hear a roar, get high immediately — do not go downstream.

Wildlife, in order of how much it matters

Rattlesnakes are present and most active in the warmer months and around dawn and dusk. Watch where you put hands and feet, especially on ledges and around rock. Most bites happen when people try to handle or kill one — leave it alone and walk around.

Scorpions and spiders shelter in cool dark places. Shake out boots and check before reaching under rock.

Everything else is a nuisance rather than a danger, provided you do not feed it.

The ground itself

Slickrock is grippy dry and treacherous wet or dusty. Proper soles matter more here than tread depth.

Lava is sharp and will shred both shoes and hands.

Cryptobiotic soil — the dark, crusted living surface between rocks — takes decades to recover from a single footprint. Stay on rock, sand or trail.

Sun

Utah has the highest melanoma rate in the United States, at roughly 46 cases per 100,000 against a national figure near 25. Shade is scarce on most trails here. Hat, sleeves, sunscreen and sunglasses are equipment, not precautions.

Navigation

Open slickrock has few paths, cairns are unreliable, and one dome looks much like another. Keep track of your line back, turn round earlier than feels necessary, and do not rely on a phone alone — signal is poor and batteries fail in heat.

Tell someone your route and your expected return. In quieter country you may genuinely see nobody.

The short version

Start early, carry too much water, never enter a canyon on an uncertain forecast, leave the snakes alone, and turn around on time. Almost nothing else goes seriously wrong here.