240,the following is a 'cut and paste' because I know nothing about weather conditions un less I can read the 'thermometer' in my back yard. I think it will clarify your recommendation to only climb during the summer months......
For a few weeks each spring (mid April through end May), the weather on Mount Everest improves just enough for adventurers to take the climb of a lifetime up the world's tallest mountain.
So from mid April until late May, hundreds of climbers take advantage of this meteorological window that only about 3,000 others have taken before them.
Scaling the world's tallest mountain is certainly not for the faint of heart.
Despite the nearly calm weather conditions usually offered up during this timeframe, climbers always have to deal with extreme cold, avalanches, unstable ground and health difficulties as a result of increasing altitude and decreasing pressure.
But for thrill seekers, it's now or wait until next year.
The summit of Everest at 29,029 feet (8,848 m) above sea level is high enough to penetrate the jet stream, a fast-moving "river of air" that can generate wind speeds of greater than 100 mph.
For a few weeks in May, the jet stream lifts north of the Himalayas, greatly reducing average wind speeds and the chance for precipitation at the top of the mountain.
This makes a trip to the summit more plausible than at any other time of the year, with climbers typically taking off during mid and late April to arrive at the summit just in time for the calmer conditions.
Climbers call the period of calm "The Weather Window."
