Above:  The PNT in the Buckhorn Wilderness. Photo by Tyler Yates.

Climate and Weather

The 1,200 mile Pacific Northwest Trail has an east-west orientation. This creates a narrow weather window compared to other National Scenic Trails. The best weather for long-distance trips on the PNT generally occurs between mid-June and mid-September. Trails are typically snow free from all but the highest elevation areas by July. In the Puget Sound, the PNT offers year-round access.  

The Rain Shadow Effect

The weather and climate across the trail corridor can vary greatly by geographic area, elevation, and season. The major mountain ranges of the PNT create rain shadows with drier and warmer east sides, which can approach desert-like climates, and much cooler and wetter west sides, which may contain rainforests.

Annual Weather Variations

Larger, annual weather patterns have caused drought to occur in the Northwest, creating conditions where wildfires are more likely to occur. When this happens, land managers alert the public with elevated fire danger levels. They may take additional steps to protect natural resources by temporarily banning campfires or certain camp stoves.

Temperatures on the PNT can vary greatly with summertime highs in the 80s and 90s in the daytime, and cooler, sometimes freezing, temperatures at night. In the mountains, storms are common; always be prepared for a few days of rain and wind. At higher elevations, it is possible for temperatures to drop below freezing or for snow to fall, even in summer.

Snow
Clothing and Rain Gear
The Weather Window
What About Visiting Outside the Weather Window in the Spring?
What about hiking outside the weather window in fall?
Snow

Annual variations in snowfall will affect the weather window for the Pacific Northwest Trail from year to year. For example, above average snow years may cause snow to persist on high elevation trails longer. You can read more about snow on the PNT, and how it affects the hiking season, here.

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. Enough snow and ice can accumulate in a single storm to make steep trails dangerous, even impassable. The weather in the Northwest also becomes much wetter, more extreme and unpredictable. Snowfall and high winds can occur more frequently in the mountains.

During winter, high levels of precipitation falls on the Olympics and Cascades with heavy rains at lower elevations and large amounts of snowfall at higher elevations.

For those prepared for snow travel, many trails along the PNT offer year-round opportunities for skiing, snowshoeing, and backcountry camping. Use caution, much of the PNT travels through avalanche terrain. You should always check the avalanche forecast when snow is present before your visit. Winter camping and avalanche skills and equipment are recommended and may be required for even short trips on the PNT in winter.

Clothing and Rain Gear

Temperatures on the PNT can vary greatly with summertime highs in the 80s and 90s in the daytime, and cooler, sometimes freezing, temperatures at night. Dressing in layers and being prepared for hot dry sections of trail, as well as cold wet sections, will by the key to having a comfortable and safe trip on the PNT.

Rain in the Northwest is often accompanied by a cold front, making for chilly or windy conditions where hypothermia is possible. Even long after rains have stopped, trail-side brush and large-leaved plants, like thimbleberry, continue to transfer moisture to clothing. In the mountains, heavy, cold rain or snow can fall anytime of the year, but does more frequently during the shoulder seasons and winter.

Although some PNT thru-hikers have experienced little rain during years of drought, it is also normal to experience periods of cold wet weather on the PNT. A light, breathable rain jacket is highly recommended for any trip on the PNT.

Due to the risk of hypothermia on the PNT, a durably waterproof storm shell is recommended over a basic polyurethane model. These products come at a higher price, but typically are more breathable and far more durable than a basic model, being constructed of thicker nylon shell fabrics. During bushwhacks and scrambles, heavier fabrics are less likely to become torn.

All waterproof fabrics work best when clean. Consider washing soiled rain gear with an appropriate cleaner if the face fabric does not bead properly. Some thru-hikers plan ahead by mailing themselves special soap so they can wash their gear mid trip to ensure good performance.

Also consider packing bottoms, such as rain pants or a kilt, to protect against wet brush and wind. Most backpacks are not completely waterproof on their own.  Keeping the contents of your pack dry is of critical importance.  This can be accomplished with a pack cover, a pack liner (odor-free trash compactor bag), or waterproof stuff sacks.

Due to stream crossings, wet brush, snow or rain, your feet will get wet no matter what. Warm socks, which insulate when wet, like wool or possum down, will help you stay reasonably comfortable until you can change into warm, dry clothing in camp.

The Weather Window

The weather window recommended for long-distance hiking on the PNT typically opens in early summer (mid June) and closes in late summer (September). Annual variations in amount of snowfall will affect the weather window from year to year. 

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. Snow and ice can make steep trails dangerous, even impassable.

Outside of this “window” the weather in the Northwest also becomes much wetter, more extreme and unpredictable. Snowfall and high winds can occur more frequently in the mountains.

Snowpack, which is at its peak in May in the Rocky Mountains, creates other snow travel hazards and challenges, in the spring and early summer. You can monitor the snowpack along the Pacific Northwest Trail, here.

Two sections of the PNT — the Wilderness Coast, Section 10 and the Puget Sound, Section 8 — are located in more temperate climates and have much longer seasons. These popular sections of trail can be visited May through October, with heavy rains, and more frequent storms, occurring in winter.

During winter, high levels of precipitation falls on the Olympics and Cascades with heavy rains at lower elevations and large amounts of snowfall at higher elevations.

What About Visiting Outside the Weather Window in the Spring?

Heavy snow and rain, at high elevations, characterize the North Cascades and Olympic Mountains every winter. Avalanches are common in winter and spring in these steep mountains. Other early season hazards include snow bridges, river fords, high-angle snow travel, “elephant traps,” and other snow travel hazards.

Special equipment and knowledge can greatly minimize the risk posed by these hidden hazards, but does not eliminate the serious risks they pose to one’s personal safety. Low angle snow on hiking trails can make progress difficult and slow. Snow can also obscure hazards, like snags, and make navigation more difficult.

What about hiking outside the weather window in fall?

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.

Resources

The Natural Resources Conservation Center provides an interactive map to monitor the snowpack in the western states.

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.

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