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Subzero cold might be uncomfortable, but at least it ensures stable snow and ice conditions. Rapid warm-ups generate a new set of backcountry perils, like avalanches, thin ice, and rock fall. Follow these tips to avoid the hazards caused by seesawing mercury.
- Review the weather It may be 22°F today, but did the thermometer jump to 40°F earlier in the week? Knowing recent highs and lows can help forecast potential risks.
- Inspect beneath Warm spells can melt snow and ice from the bottom up, leaving a fragile shell over a rotten void. Tread carefully near thawing streams and large boulders (which absorb solar heat); probe the surface with trekking poles as you go.
- Look up Thaws expose bare rock and dislodge stones and icicles, making falling objects a serious menace. Avoid traveling under cliffs, especially when the slope above receives direct sunlight.
- Start early Colder night air can re-freeze mushy snow into a solid surface, making mornings the best time to travel without post-holing up to your knees.