La Niña Is Coming—Why Skiers Should Be Wary of Tree Wells

What Is a Tree Well?

Tree wells form around the base of evergreen trees (like firs and hemlocks) on ungroomed runs, particularly after a large amount of snow has fallen. The snow in these voids is loose but compactable. If a skier falls headfirst, they might plunge multiple feet under the snow’s surface, becoming stuck or, in more dire cases, suffocating.

Deaths from these incidents are referred to as snow immersion suffocation, or SIS. While tree wells aren’t the only culprit in SIS accidents—there are other ways that skiers get buried under the snow—they account for 70% of them, according to deepsnowsafety.org.

Staying off ungroomed terrain that hasn’t been compacted by a snowcat is the easiest way to avoid tree wells. But as almost every skier knows, fresh tracks are one of the best parts of a day in the mountains. Following these tips can help you stay safe from tree wells while still enjoying powdery, off-piste terrain.

Staying Safe From Tree Wells

Never ski alone and always keep your partner in sight: If hunting for powder is your goal, don’t venture into the trees alone. Bring a buddy and keep them in sight at all times. This way, a helping hand is never too far away. Another sobering statistic per deepsnowsafety.org: 90% of skiers and snowboarders rescued surveyed in SIS research experiments couldn’t have escaped on their own. Don’t have a pal on any given day? Stick to groomed trails.

Wear a whistle or radio: Loud, high-pitched whistles can be worn close to the chest, providing an audible lifeline in case you become immersed in snow. Keep the whistle close to your mouth so you can reach it easily, even if your arms are trapped by the snow. Chest mounted radios are another alternative for communication, and packable avalanche shovels can prove useful in tree well rescue situations.

Ski in control: Stay defensive, give trees a wide berth, and anticipate the twists and turns of whichever run you’re skiing. 

What If You’re Trapped in a Tree Well?

Deepsnowsafety.org recommends the following steps for skiers or snowboarders stuck in a tree well.

• Get your partner’s attention by yelling or using a whistle.
• Do whatever you can to keep your head above the surface of the snow, including rolling, grabbing tree branches, or the tree trunk. If possible, keep your feet below the level of your head.
• If you become immersed, make a space around your face and protect your airway—resist the urge to struggle, it could compromise your airspace and entrap you further.
• Stay calm to conserve air.
• Trust your partner is on their way.
• If possible, use your cell phone to call ski patrol or the resort’s emergency number.

How Likely Is La Niña This Year?

As of its latest update, the Climate Prediction Center said on September 11, 2025, that the likelihood of La Niña developing between October and December is 71%. Those odds decline to 54% once December starts and winter begins.

Forecasters anticipate a weak La Niña this year, which typically translates to less consistent winter weather impacts. Still, historically, weak La Niñas have corresponded with above-average snowfall in the Pacific Northwest.

Washington, in particular—where skiers flock to Stevens Pass, Mt. Baker, and Crystal Mountain—remains within La Niña bullseye, even if the signal isn’t as strong when the climate pattern is weak.

However the forecast shakes out, though, stay vigilant. A good storm or two can produce dangerous tree well conditions.