The official definition of a winter ascent in China and Tibet seemed to have been resolved with the January 2005 ascent of Shishapangma by Piotr Morawski and Simone Moro. They were issued a certificate from the CTMA (China Tibet Mountaineering Association) stating they had made the peak’s first winter ascent. This came shortly after the late Jean-Christophe Lafaille claimed a winter ascent of the same peak on December 11, 2004; the Frenchman cited Nepal’s regulations.
In Nepal the official winter season runs from December 1 to February 15, dates that contrast significantly with the accepted Northern Hemisphere calendar winter that spans from December 21 to March 20. Most climbers, and particularly those in the vanguard of serious Himalayan winter mountaineering, disagree with Nepal’s rules. Prior to 2004, all winter ascents of 8,000m peaks had been done after December 21. Krzysztof Wielicki, a veteran of seven Himalayan winter expeditions, explained the Nepal Ministry of Tourism’s logic for setting the date at December 1: this was to be the day when an expedition arrived at Base Camp. The arbitrarily designated departure date of February 15 may have been set because Sherpas needed a rest period before starting work in the pre-monsoon season. In Nepal there can be a world of difference between the first week in December, when it is not unusual to find conditions similar to late October, and the end of the same month, when the jet stream has lowered and snow has fallen.