60s and 70s, but nighttime lows still occasionally dip below freezing. The most precipitation (an average of around 2 inches per month) falls during May and the “June monsoon.”
Mature bighorn rams with horns in full curl are often seen around Bunsen Peak (Trail 3).
The prime summer hiking and backpacking season starts as the snow line progressively retreats up mountainsides until the highest passes are clear—typically by late July in Yellowstone, and early August around the highest Teton passes. Elk and bison continue to drop calves until the summer solstice (June 21), the longest day of the year. The opening of Yellowstone’s fishing season (the first Saturday of Memorial Day weekend) coincides with the start of the stonefly hatch—when mosquitoes and biting flies really hit their stride. Wildflower-watching heats up soon after snowmelt and peaks around mid-July in most of Yellowstone, a bit later at higher elevations and in the Tetons. Midsummer, daytime temperatures are typically in the 70s (and 80s at lower elevations). Nights remain cool, in the 40s and 30s, with the odd frosty spell.
The courting and mating season (the rut) begins as early as late July. During this period, it’s especially important to give elk and bison a wide berth on trails. Mosquitoes and other biting pests finally die down in August; that’s also when berries are ripe for the picking in riparian zones. July and August are the driest months, but afternoon showers are still fairly common. Blooming goldenrod and gentians are reliable indicators of the coming of autumn.
Fall colors start to appear in the riparian zone by mid-August and peak around the autumnal equinox (September 21), with slight variations according to elevation. Vibrant yellows, reds, and oranges persist on Yellowstone’s Northern Range until early October, when the first significant snowfall usually occurs. Temperatures can remain surprisingly pleasant through October, but nighttime lows often plunge into the teens. Squirrels, chipmunks, and other rodents frantically preparing winter seed caches are a sure sign of another impending long winter.
Trail Selection
Three criteria were used in selecting trails for this guide. Only the premier day hikes and overnight backpacking trips are included, based on beautiful scenery, ease of access, and diversity of experience. Many of the trails are very popular, while several others see infrequent use. If you are fortunate enough to be able to complete all the trips in this book, you will gain a comprehensive appreciation for the complex beauty of one of the world’s most scenic and intact temperate-zone ecosystems.
Nearly half of the trails included in this guide are out-and-back trips, requiring you to retrace your steps back to the trailhead. Forty percent of the routes are full or partial loop trips, with the remaining six routes being point-to-point trips that are worthy of the required vehicle shuttle. For these, you’ll have to travel with friends or family who don’t mind picking you up at the end of the day, or arrange a commercial shuttle service for longer trips. It’s fairly common for people to hitchhike short distances through the parks to get to the trailhead before hiking back to their car.
Key Features
Top Trails books contain information about the features of each trail. Yellowstone and the Tetons are blessed with diverse terrain—no matter what your interests, you’re sure to find a trail to match them.
Water lovers and anglers will find plenty of pristine lakes, rivers, and streams, while peak-baggers will be spoiled by the choice of world-class alpine panoramas. The abundant open meadows are graced with riotous wildflower displays, and aspen groves provide plenty of fall color. All these features combine to make Greater Yellowstone a photographer’s paradise. With a bit of planning, the opportunities for camping, fishing, boating, swimming, and wildlife-watching are endless.
Multiple Uses
All the trails described in this guide are suitable for hiking. Although all the trails are equally legal for jogging, the vast majority are not suited for it, as running can incite predatory behavior in some wildlife. The only exceptions are the few gravel and paved roads in more developed areas that also allow bicycling, notably the road to Lone Geyser in Yellowstone. Where applicable, trail descriptions note where routes receive heavy stock use by horse packers and llama outfitters. Kayaking and canoeing are increasingly popular ways to reach some of both parks’ more secluded backcountry campsites—for example, Shoshone Lake in Yellowstone and Leigh Lake in Grand Teton. Fishing is superb in both parks too. As in most national parks, pets and mountain biking are prohibited. Winter use is limited but growing in both parks, with cross-country skiing, snowshoeing, and snow-coach tours becoming more popular as snowmobiling is increasingly restricted.
Trail Safety
Dramatic elevation changes pose a possible danger to visitors arriving from near sea level. Signs of altitude sickness include headache, fatigue, loss of appetite, shortness of breath, nausea, vomiting, drowsiness, dizziness, memory loss, and diminished mental acuity. A rapid descent generally alleviates any symptoms. The best advice is to eat lots of carbohydrates prior to the trip, acclimatize slowly, avoid alcohol and heavy foods, and drink plenty of fluids.
Burns from thermal features are a common cause of death and serious injury in Yellowstone. Follow posted regulations about off-trail travel, don’t traverse thermal areas after dark, and don’t bathe in thermal waters that aren’t National Park Service–approved (see “Bathers Beware”).
Ticks are a nuisance from mid-March through mid-July in the lowest-lying areas. Wear insect repellent, tuck your shirt and pant legs in, and check your body often. Depending on elevation and the rate at which the previous winter’s snowpack melts, the peak of the mosquito season hits the backcountry in June and July and abates in mid-August. Repellent, netting, and protective clothing are your best forms of protection.
Most of Yellowstone’s backcountry river crossings intentionally lack bridges, and many fords are dangerous (over thigh-deep) until at least July. Check current conditions during trip planning, and when in doubt, pick another route, or turn back.
Dehydration is a concern on longer trails where water is lacking. The presence of Giardia means that all water should be boiled, filtered, or otherwise treated before drinking. Keep your hands clean to avoid transmitting nasty microbes to your hiking companions.
Sunburn is a concern, especially at higher altitudes. Sun protection, sunglasses, and a good wide-brimmed hat are essential. Due to the possibility of rapid weather changes, hypothermia is a concern year-round. Most hypothermia cases happen when air temperatures are between 30°F and 50°F. Always check the weather forecast before heading out, and carry extra warm and waterproof gear. It’s not uncommon to experience four seasons during a midsummer hike.
Cell phone coverage is sketchy at best throughout both parks, though it has improved greatly in recent years and is available at most junctions in Yellowstone. In general Verizon offers the best coverage. That said, you should not count on your phone as a reliable means of communication in an emergency, especially in the backcountry.
Bathers Beware
Soaking directly in thermal waters is not officially allowed in Yellowstone, so as to protect both bathers’ skin and the park’s unique thermophilic microbiological resources. Swimming is allowed in a few places where thermal runoff mixes with cold-water sources, such as the Boiling River (Trail 2) and the Firehole River Canyon
