Hiking, biking, and trails in Colorado
Altitude, weather, and day-hiking safety in Colorado
A calm plan for thin air, lightning, changing temperatures, navigation, layers, water, and the decision to turn around.
Thin air
Altitude can turn a normal hike into a hard one
Ease into elevation
Altitude illness is possible above 8,000 feet. If you are coming from low elevation, build in time to adjust before a high route.
Know the early signs
Headache, unusual tiredness, nausea, vomiting, or poor appetite can be altitude illness.
Do not keep climbing through symptoms
CDC says not to travel higher until symptoms are gone. If symptoms worsen while resting, move to a lower elevation.
Treat confusion or trouble walking as urgent
Confusion, loss of coordination, or serious trouble breathing can be life-threatening. Descend immediately and seek emergency care.
Thunder
Plan the safe shelter before the clouds build
The National Weather Service says no place outside is safe in a thunderstorm. Move toward a substantial building or enclosed hard-topped metal vehicle as soon as thunder is heard. A tree, picnic shelter, tent, rock ledge, or open summit is not safe shelter.
Carry enough to wait, turn around, or walk out late
- Bring an offline map, headlamp, water, food, warm layer, rain shell, sun protection, and basic first aid.
- Tell someone the route and return time, especially where service is weak.
- Check the forecast, watch the sky, and choose a turn-around time that gets the group off exposed ground before expected storms.
- Wait at least 30 minutes after the last thunder before returning to an outdoor activity.
- Turn around early enough that the return does not depend on perfect weather or a phone battery.
Take this with you
Before a high trail day
- ✓ The group has had a reasonable chance to adjust to the elevation.
- ✓ The route forecast and any weather alerts were checked this morning.
- ✓ Everyone knows the turn-around time and altitude warning signs.
- ✓ Layers, water, food, light, navigation, and a shared return plan are packed.
Official sources and review
Check the current rule before you act
These links go to the agencies that control this part of the trip. Use the exact page, license, listing, map, order, or confirmation for your situation.
Use this carefully: This is general outdoor guidance, not medical advice or a promise that a route is safe. Weather and altitude illness can change quickly. Stop, turn around, descend, call 911, or seek medical help when the situation calls for it.
Keep going
The other parts of hiking, biking, and trails in colorado
Find the right trail
How to use COTREX, identify the land manager, compare route demands, and confirm parking, permits, and current access.
Access, pets, and etiquette
How land managers, private boundaries, permits, seasonal closures, dogs, horses, and posted trail rules fit together.
Bikes and e-bikes
How to check whether a Colorado trail allows a bike or e-bike, which manager controls the route, and what to settle before riding.