New Delhi, June 17 -- The climbing season on Mount Everest peaks in late May and early June every year. Extreme weather patterns at this location and altitude mean the main climbing season is remarkably short, perhaps only a few weeks between the winter freeze and monsoon storms.

Even within that time, the precise location of the jetstream that accelerates wind speeds at the summit creates pinchpoints of ideal climbing conditions, leading to images of long queues of mountaineers at particularly challenging points such as the Hillary Step - named after one of the two men who first climbed Everest on May 29 1953.

In the 30 years after Edmund Hillary and Sherpa Tenzing Norgay first stood at the summit, only 150 men and women matched their ...