Mountaineering success – defined here as reaching the summit and returning safely – depends on both climber-dependent skills and external factors such as mountain conditions and weather. While athletic ability is often highlighted as the key to success, the role of favorable weather is harder to quantify and frequently overlooked. In this study, we analyze 170 ascents nominated for the Piolet d’Or since 1991—an annual international award that we use as a proxy for groundbreaking ascents. Using ERA5 reanalysis climate data, we assess the rarity of weather windows for each ascent duration. Our results show that most ascents benefited from exceptionally favorable weather conditions relative to the 30-year climatic average. While our results focus on a niche aspect that is elite mountaineering, we also discuss the role of climate change in shaping long-term mountain conditions worldwide, with impacts that may be either beneficial or detrimental depending on the region.