When Shoulder Season Becomes Winter (and How to Notice in Time)

The deadliest hikes in the lower 48 happen in October. People plan a 70°F day-hike, get a 25°F afternoon, and lose the route because they're shivering. Five signals our team reads.

1. Trailhead temperature minus elevation

Subtract 5°F per 1,000 ft of climb. If the trailhead is 50°F at 7,000 ft and you're going to 12,000, the summit will be ~25°F before wind chill. October trailhead temps lie.

2. Cloud height vs ridgeline

If clouds are sitting on the ridge you're aiming for at 8am, that's your forecast — wind, low visibility, possible precip. Don't go up.

3. The sun's arc

Sunset by 6pm in October at most US latitudes. Plan for 2pm turnaround in any October day-hike above 8,000 ft. Headlamps stay in the pack until dark; they aren't a substitute for daylight on a snow-covered trail.

4. Mud / dampness above the snowline

If the trail is muddy at 9,000 ft on a sunny day, that's frozen ground thawing — meaning yesterday it was below freezing. Tomorrow it might be again.

5. Other hikers' gear

If everyone coming down is in puffy jackets and gloves, you're not overdressed. Trust the down-trail feedback.

What we always carry October–April above treeline

Microspikes (4 oz, $40)

Headlamp (Black Diamond Spot 400)

Synthetic puffy (Patagonia Nano Puff, not down)

Garmin inReach Mini 2

1L extra water

Bivy / emergency blanket