trout, and lake chub.
Bald eagle nest: Eagles are often found fishing for trout around Heart Lake (Trail 22).
Six species of reptiles (prairie rattlesnake, bull snake, valley garter snake, wandering garter snake, rubber boa, and sagebrush lizard) and four decreasingly common species of amphibians (boreal toad, chorus frog, spotted frog, and tiger salamander) are found in Yellowstone. Encountering a poisonous prairie rattlesnake in Yellowstone’s low-lying Northern Range is unlikely but possible.
More than 12,000 insects, including 128 species of butterflies, provide fodder for many quick-tongued predators. Of greatest concern to hikers are mosquitoes (see Trail Safety).
When to Go
As two of North America’s most popular summer destinations, both parks have the unfortunate reputation of being overcrowded, especially Yellowstone. This certainly can be true on major holiday weekends, on heavily trafficked roads, and at campgrounds and must-see attractions, but solitude is not hard to come by—if you know where to look.
Both parks are four-season recreation destinations. Less than 5% of Yellowstone’s visitors arrive between November and April. Likewise, in Grand Teton 80% of visitors arrive between June and September. Annual Yellowstone visitor numbers have risen noticeably in the past 15 years to almost 4 million (most coming via the West Entrance), while Grand Teton averages around 3 million.
Thankfully, even in summer, escaping the crowds is reasonably easy, especially in Yellowstone. To find solitude, head for the backcountry. Surveys by the Park Service found that less than 1.5% of visitors apply for a backcountry permit in Yellowstone; only half of 1% do so in Grand Teton.
To avoid crowds, especially in the frontcountry, the usual rules of thumb apply: visit midweek instead of on weekends, and during spring and fall shoulder periods. Some of the finest hiking conditions coincide with diminishing crowds after Labor Day weekend and the peak of fall-foliage colors. The last week of August is a good time to come, for its combination of summer weather and slightly lighter crowds.
Accommodation in Yellowstone is a different matter. During the peak months of July and August you need to have booked your park accommodation at least six months in advance (some rooms sell out a year in advance). Even the reservable Xanterra campsites are often booked up a month in advance in summer. Unreservable park campgrounds are generally full by noon, with many campgrounds full by 9 a.m. Reservations are essential in Yellowstone. There’s more room to move in Grand Teton, since most of the campgrounds are nonreservable, but you’d be wise to book RV sites in advance and make your lodge reservations at least six months ahead.
Weather and Seasons
Throughout Greater Yellowstone, conversations (and tall tales told by the fireplace over a posthike pint) are peppered with anecdotes about the region’s famously mercurial weather. Snowfall has been recorded every single day of the year here, so the best advice is to always come prepared for the possibility of extreme conditions and four seasons in a single day. Locals claim there are nine months of winter and three months of relatives. This isn’t that far from the truth. Perhaps the most reliable climate-related axiom is, “If you don’t like the weather, just wait five minutes.” In any case, on any given day, Yellowstone is often the coldest spot on a US weather map.
Always be ready for afternoon thundershowers (locally called “rollers”) and to beat a hasty retreat from the higher elevations when lightning threatens. Because conditions on the trails change as quickly as the weather, it’s best to check in with a ranger station before hitting the trail, even if you’re only going for a day hike.
Given the right disposition, conditions, and over-snow travel gear, winter can be the ideal season to explore the parks in relative tranquility. During winter, the mercury hovers around 0°F during the short daylight hours, with occasional highs in the 20s. Subzero overnight lows are the norm. Infrequent warm “chinook” winds push daytime highs into the 40s. Annual snowfall averages 150 inches in most of Yellowstone, with 200 to 400 inches routinely recorded at higher elevations.
Yellowstone’s winter tourism plan has been in flux for the last decade, as the park tries to balance the demands of local communities while limiting the number of snowmobiles through the park each day. As of winter 2016–2017, Yellowstone National Park allows a maximum of 110 daily “transportation events” (defined as one snow coach or group of snowmobiles) to enter the park. Only half of these “events” can be snowmobiles. The plan also allows one noncommercially guided group of up to five snowmobiles to enter through each park entrance every day. Noncommercial guides must get a noncommercial snowmobile access permit, which is awarded by lottery at recreation.gov starting September 1. Leftover permits are available on a first-come, first-served basis starting in November. Permits cost $40 per day, plus a $6 application fee. Each snowmobile driver must have completed a free online certification training course. Snowmobilers can drive their own machines or rent them at park gateway towns, as long as they meet or exceed available technology standards. In addition, a dozen operators offer increasingly popular guided tours by snow coach (vehicles such as vans or buses that have been adapted to travel over snow). Skiers and snowshoers don’t need a guide, and the parks have many groomed and ungroomed trails to choose from.
Yellowstone and Grand Teton National Parks Spring Bicycling Period
Weather permitting (after the winter snowmobiling season ends in mid- to late March and before the park opens to wheeled vehicles, typically the third Friday in April), there’s a glorious opportunity for bicyclists, hikers, joggers, in-line skaters, roller skiers, and the like to explore Yellowstone between the West Entrance and Mammoth Hot Springs, via the nearly auto-free Grand Loop Road. Call 307-344-2109 to confirm the Spring Bicycling Period schedule. There’s no in-park lodging open (Mammoth Campground is open year-round, or you can stay in nearby gateway towns). The 6 miles between the East Entrance and the east end of Sylvan Pass and the South Entrance road to West Thumb Junction also sometimes has limited access. The road from Madison Junction to Old Faithful typically does not open.
In Grand Teton, the beautiful 15-mile section of Teton Park Road between Taggart Lake Parking Area and Signal Mountain Lodge is similarly open to nonmotorized use in the month of April.
Though February sees some frosty but crystal-clear days of sunshine, snow blankets most of both parks well after the vernal equinox (March 21). The appearance of migrating mountain bluebirds and the emergence of Uinta ground squirrels are reliable indicators of the arrival of spring, usually in the second half of March. Depending on snow conditions, nonmotorized exploration (including hiking, bicycling, jogging, in-line skates, and roller skis) is permitted in Yellowstone between the West Entrance and Mammoth Hot Springs from mid-March through the third week in April.
The spring hiking season begins as snow starts to melt from the lowest-lying trails (as early as May on Yellowstone’s Northern Range, a bit later around Jackson Hole) and after trail maintenance crews clear winter deadfall. Early-season hiking coincides with the reemergence of ravenous bears and their newborn cubs from their dens as they prowl for elk calves. Many of the Yellowstone trails that pass through Bear Management Areas are off-limits from May into June. Hiking can be superb before crowds begin to arrive for Memorial Day, when both parks are a hive of calving, nesting, spawning, and blooming activity. River fords are most dangerous in May and June, when snowmelt-fed waterfalls are also the most spectacular. Daytime temperatures
