“How long is the hiking season?”
“When should I start my trip?”
Answers to these questions can vary each year. This guide provides useful tools to monitor the snowpack across the Pacific Northwest Trail system and estimate when key areas on the trail will become snow free.
Snow can make for hazardous conditions–this guide will also present basic information about the hazards of snow travel on the PNT so that you can plan a trip that is well-suited to your skill level. Remember, snow storms can happen any time of year on the Pacific Northwest Trail. Always be prepared for a few days of cold, wet weather, even in summer.
Monitoring Snowpack and Trip Planning
From year-to-year, snowfall in the Northwest can vary significantly and can affect the hiking season and trail conditions for the Pacific Northwest Trail.
Using SWE Charts
The SWE Charts below display current averages of Snow Water Equivalent as compared to a ~30 year average for basins in each state. These charts can be used to estimate when the trail corridor might become snowfree each summer.
When the current snowpack is greater than the historic average (more than 100%), then trails will generally hold snow longer, and the weather window can be delayed by as much as two or three weeks in some areas. Note that predictions early in the season may be subject to change as new data is collected from storms later in the season.
Using the NRCS Interactive SNOTEL Map
The interactive SNOTEL map shown below is configured to display the depth of the snowpack in inches at the SNOTEL monitoring sites nearest the PNT. This information can be used to form a rough estimate of the amount of snow currently on the trail by comparing snowpack at various locations, and by looking closely at the elevation of the site.
Be aware that snow depth on the trail at higher elevations can be much greater than what is shown here and can also vary significantly due to other conditions.
Choosing a Start Date and Trip Planning
With a relatively short season, limited by the weather window, choosing a good time to begin a Crown-to-Coast adventure on the PNT is important. An “early start” will involve snow travel and its associated risks, while a “late start” will leave less time to complete a thru-hike before snow and rain arrive in the fall. Paying attention to snow conditions and learning how trail snow could affect your trip will help guide your decision about when to start.
If trail snow could be present when you plan to start, ask yourself and each member of your party if they are fully prepared for snow travel. It is recommended to plan your trip around the least physically fit and experienced person in the party, because they will set the pace for the entire group. If you find the extra effort and risks described below to be undesirable, you can avoid them by planning a conservative itinerary with a start date delayed by a week or two from the average.
Remember, backcountry camping permits for Glacier and Olympic National Park will also be a factor–are they available for your desired start date?
Be aware that Park Rangers may approve or deny backcountry permits or recommend alternate routes at their discretion. Please respect their experience and knowledge of local conditions. If you are fully prepared for the risk and have mountaineering experience, be sure to communicate this while applying for your permit. Most PNT thru-hikers wait for snow to melt on the trail or the high mountain passes before starting their trips.
Hiking westbound in Glacier National Park
If the snowpack shown in the Montana SWE Chart, shown above, is 100% of normal, expect most trails on the PNT in the Glacier National Park to be snowfree by late June. If the snowpack is greater than 100%, snow can persist on high-elevation trails in the park until early July. It is always possible for late-season storms or other weather conditions to affect the start of the hiking season. Up-to-date info on trail conditions in the park can also be found on the park’s website. Note that seasonal suspension and plank bridges are not installed until mid-July.
Snowpack on high mountain passes on the PNT–Stoney Indian Pass on the PNT primary route, and Boulder Pass on a PNT historic alternate–can leave the PNT impassable to most users and create snow travel hazards which require special equipment and knowledge to safely traverse.
Hiking eastbound in Olympic National Park
If the snowpack shown in the Washington SWE Chart below is 100% of normal, expect high elevation trails on the PNT in the park to hold snow until late July. If the snowpack is greater than 100%, snow can persist on steep alpine trails in Olympic National Park until August. It is always possible for late-season storms or other weather conditions to affect the start of the hiking season.
Detailed information about trail conditions in the park are regularly updated by the park.
High elevation trails in Olympic National Park can follow very steep terrain. Snowpack can make trails impassable to most users and create snow travel hazards which require special equipment and knowledge to safely traverse.
Snow Travel in the Shoulder Season
The Spring Shoulder Season and Snow Travel
This guide alone can not prepare you for the hazards of snow travel. Its purpose is to offer basic information about the potentially life-threatening conditions early season users could encounter on the PNT. Reading this guide will help users without proper experience or training make an informed self assessment about their readiness to apply for a backcountry permit for the PNT in the shoulder season.
Special equipment and knowledge can greatly minimize the risk posed by snow travel, but does not eliminate the risk to one’s personal safety. Rescue for even minor accidents, can be delayed or complicated by snow and weather conditions and avalanche risk for search and rescue teams.
In the spring shoulder season, the snowpack is dynamic, and can change significantly day-to-day, and even by the hour. In early morning, snow covered trails may be slick or covered in surface ice after freezing overnight. This time of day, the snowpack is usually consolidated, making travel more efficient. Later in the day, solar energy accelerates snow melt and snow will be less firm, making progress more difficult and creating other potential hazards, including risk of wet loose avalanche.
Along the trail, conditions can vary. Snow depth can increase with elevation, and can vary with aspect. Expect different conditions on sunny south-facing slopes than on shaded north-facing slopes. Wind also shapes snow features and snowpack. In wind prone areas, like mountain passes, wind can sculpt drifts and cornices which make travel difficult and dangerous. It can also freeze snow, creating icy conditions.
Be wary of snow around objects; rocks and logs hold the sun’s energy and can transfer it over time, melting the snow around them. Surface snow may look solid, but can conceal hidden hazards, like tree wells and elephant traps or snow moats, which can cause fall related injuries or even trap victims in deep snow wells. Experience can help visitors to read the surface of snow for hidden danger and to choose routes around potential problem areas.
In forested areas, the trail and the contours of the forest floor may be completely or partially hidden. Around logs, snow can melt creating “snow gators” which can cause lower body injuries when a hiker unexpectedly postholes, or plunges, through the surface of the snow, striking the object, or by becoming restrained by the object while the rest of the body remains in motion.
Snowpack can affect route-finding and make navigation more difficult by concealing the trail. Much of the PNT is not marked or blazed, and in some short sections, bushwhacking is required to travel between existing trails. Early in the season, trail conditions may also make navigation more difficult. Crews are unable to logout or brush trails when significant amounts of trail snow are still present.
Obstacles, like cornices and large consolidated snow drifts, can render short areas of the trail impassable to most users. Experience is required to assess these risks and to choose a safer route to detour around them.
Snow Travel Skills
Steep slopes of mountain trails may go unnoticed in summer, but when covered in snow, these trails become impassable without proper equipment and experience. In the spring shoulder season, snow fields can be intermittent along the trail. Even a small snowfield can create a fall risk. Without snow travel experience and equipment, a fall could send a visitor sliding toward hazards like rocks, or over a cliff.
The ability to use an ice axe to prevent a fall or to self-arrest in the case of a fall, can be critical to traverse steep trails and obstacles. Learning to accurately determine the risk of a fall by assessing one’s “fall line” in the case of an uncontrolled slide, is a critical part of traveling across snow.
Creek crossings can be particularly dangerous in the shoulder season. Large amounts of spring run-off from melting snow can make it difficult to keep one’s footing while fording creeks. Naturally formed snow bridges across creeks may be unstable and can give way under the weight of a backpacker, trapping them in swift moving water.
The Fall Shoulder Season
Milder summer temperatures in the Pacific Northwest typically change to cooler, wetter weather at lower elevations in late September.
In the Northwest, the transition from mild weather in summer, to severe winter weather in fall, can happen very suddenly. Early fall storms can bring feet of snow, or cold heavy rain, which make backcountry conditions more difficult. This time of year, enough snow and ice can accumulate in a single storm to make steep trails very dangerous, even impassable.
Late season visitors should be aware that Glacier National Park typically begins to remove seasonal bridges and close trails in late September.
Much of the PNT travels through avalanche terrain. Avalanches are common in the Olympics, Cascades, and Rocky Mountains in winter and in spring. If you’re planing to hike where snow is present, you should always check the avalanche forecast before your visit.
Snow travel and avalanche skills and equipment are recommended, and may be required, for even short trips on the PNT in winter. It is recommended to prepare for your winter or early shoulder season trip on the PNT by taking an avalanche awareness course for winter trips in avalanche prone areas.
The Northwest Avalanche Center provides detailed forecasts for the Olympic Mountains and North Cascades.
The Idaho Panhandle Avalanche Center provides avalanche forecasts for the Selkirk Mountains and the Purcell Mountains.
The Flathead Avalanche Center provides avalanche forecasts for the Rocky Mountains and the Whitefish Range.
Earn confidence in the outdoors and prepare for your winter or spring shoulder season trip on the PNT by learning snow travel skills and taking an avalanche awareness course, before you go.
Skills for Climbing, Hiking, and Moving Across Snow
By author: Mike Zawaski
Mountaineering: The Freedom of the Hills, 9th Edition
For nearly 60 years it’s been revered as the “bible” of mountaineering–and now it’s even better than ever.
The Mountaineers of Seattle, Washington offer a range of low-cost outdoor education courses.
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