Bears

Your safety is not guaranteed, but there are several ways you can increase your safety while hiking in Yellowstone. We recommend the following while hiking in the park’s backcountry:

• Be alert: Avoid surprising bears by looking for fresh tracks, scat, and feeding sites (signs of digging, rolled rocks, torn up logs, ripped open ant hills).
• Hike during daylight hours: Avoid hiking at dawn, dusk, or at night when grizzly bears are most active.
• Stay on maintained trails: Research in Yellowstone has shown that people are more likely to be attacked by a bear when hiking off-trail.
• Avoid carcasses: Bears will guard and defend carcasses against other scavengers or humans. Dead ungulates will attract and hold many bears near the carcass site. If you find a fresh carcass, leave the area immediately by the same route you approached. Report all carcasses to the nearest ranger station or visitor center.

Drinking Water

As a safeguard against Giardiasis, other parasites and bacteria, we recommend that you boil, filter, or chemically treat all drinking water. Waters may be polluted by animal and/or human waste. Intestinal infections from drinking untreated water are increasingly common.

Hypothermia

Rain, wind, sleet, and snow can be deadly if proper precautions are not taken. Always bring rain gear and extra clothes for warmth. To avoid hypothermia, stay dry, stay out of the wind, and avoid getting chilled. Put on rain gear before you get wet and warm clothes before you start shivering. Most hypothermia cases happen in air temperatures of 30–50° Fahrenheit. Wear a hat and gloves to conserve body heat.

If you cannot stay warm and dry, assess and alter your plans. Remember that you are only as strong as the weakest person in your group. Persistent or violent shivering is a clear warning that someone is on the verge of hypothermia. Other symptoms include slow/slurred speech, loss of dexterity, exhaustion, incoherence, and drowsiness. When someone is hypothermic, find shelter and make camp. Get out of wind and rain. Remove wet clothing. Get into dry clothing and a sleeping bag. Provide warm, non-alcoholic drinks.

Stream Crossings

Few of Yellowstone’s rivers or streams have bridges, and many cannot be crossed until July or later. Even in late summer, water levels can rise quickly after rainstorms or from snowmelt in the high country on warm afternoons. The water can be cold, fast, and more than thigh-deep, making any attempt to cross perilous. Trying to ford deep, swift water has resulted in loss of gear, injury, and death. Carefully check your itinerary on a topographic map for stream crossings, and ask about river conditions at a ranger station before beginning your trip. Don’t be afraid to turn around if conditions are dangerous. Before you ford a river, make sure everyone in your group is comfortable doing so.

Thermal Features and Geyser Basins

Burns from thermal features are a common cause of serious injury and death in the park. Check at a ranger station before you go exploring. Foot travel in all thermal areas must be confined to boardwalks or maintained trails that are marked by official signs. Don’t approach or shortcut through geyser basins after dark when there is greater danger of stepping into a hot spring. For your safety and for the protection of thermal features in Yellowstone, it is illegal to swim or bathe in any water that is entirely of thermal origin. Hot springs contain algae, bacteria, and fungi found nowhere else in the world: soaking or wading in springs can destroy these life forms. Throwing objects like rocks or sticks into thermal features is prohibited since doing so can clog vents and alter the flow and temperature of the water. Food and smoking are not allowed in thermal areas.

Ticks and Mosquitoes

From mid-March to mid-July, grassy, brushy, low elevation areas (4,000–6,500 feet) are ideal tick habitat in Yellowstone. Wear repellent even on shoes, socks, cuffs, and pant legs. Tuck your pant legs into your socks and your shirt into your pants. Check your clothes and your body often. During the June and July, mosquitoes may be widespread around lakes and streams, especially in wet areas. Mosquitoes tend to diminish in mid-to-late August. Repellents, netting, and wearing clothing with long pants and sleeves are the best options for enduring insects in Yellowstone.

Wayfinding

Yellowstone’s trails may be hard to follow due to infrequent use, missing markers, recent fires, or large meadows where the trail is not clear. We strongly recommend people carry a compass and topographic map and know how to use them.

Weather

Yellowstone can experience winter-like weather any time of year. Calm, sunny mornings can abruptly turn into fierce, stormy days. Gusty, south-to-southwest winds are common in the afternoon. Rain and lightning often follow. If you’re hiking or boating when storms approach, get off the water, ridges, and open places. Thick forests of equal height offer better protection from lightning than meadows. Nighttime temperatures can drop into the 30s and 40s. Depending on elevation, temperatures may even fall into the 20s with a light freeze...even in July. Summer daytime temperatures are usually in the 70s and 80s. June can be cool and rainy. July and August tend to be drier, with afternoon thundershowers common.