Denali defies simple altitude comparisons. At 6,190m it sits below Aconcagua (6,961m), yet its overall success rate is 12 points higher — not because it is easier, but because the self-selection of permit holders is more rigorous. NPS registration, mandatory expedition logistics, and the cost and commitment required to reach Alaska filter out underprepared climbers before they set foot on the glacier.

How to read these numbers: Success is defined as reaching the 6,190m summit. Data covers all NPS-permitted expeditions 2000–2025. The guided rate reflects commercial guiding programs; the independent rate reflects self-organized teams without a contracted guiding company.

Denali’s season runs April through July, with the statistical peak firmly in late May and early June. The extended daylight of the Alaska summer gives teams flexibility on summit day, but the jet stream and arctic weather systems define the actual windows.

The last two weeks of May and first week of June consistently produce the highest summit rates. Teams departing Talkeetna in this window benefit from stable high-pressure systems that settle over the Alaska Range after the spring transition.

The West Buttress accounts for over 95% of all Denali attempts. Success rate differences between routes reflect both objective difficulty and the experience level of climbers self-selecting for each line.

The 18-point gap between guided and independent success rates on Denali is the largest of any peak in this database. Guides enforce the cache-carry discipline and rest day schedule that independent teams frequently compress under schedule pressure.

Experience is self-reported on NPS registration forms. A climber with multiple 6,000m summits but no expedition background often fares worse than expected — cold management and expedition pacing are distinct from altitude experience.

From NPS ranger reports and self-reported permit exit interviews, 2010–2025, West Buttress route.

Denali has the best-staffed high-altitude rescue operation in North America, run by NPS rangers stationed seasonally at 14,200ft. Despite this infrastructure, rescue incidents are significantly more frequent than on comparable peaks due to extreme cold and the scope of Denali’s demands on underprepared teams.

Rescue incidents are 2.1× higher among independent climbers. Cold injury requiring evacuation is the most common rescue cause — distinguishing Denali from all other peaks in this database.

Denali’s success rate has been the most stable of any peak in this database over 25 years — weather-driven variance of ±10 points between good and poor seasons, but no significant long-term trend in either direction.

The most significant single-year drop was 2003, when persistent storm systems through May reduced summit rates to 38%. The 2012–2016 period saw elevated success rates correlating with more stable late-spring high-pressure systems.