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Clear skies, calm breezes and a panoramic view of majestic summits covered in snow - that is the fall experience that hikers on the world's highest peak have come to love.

However that appears to be changing.

Shifting Weather Patterns

Climate scientists say the rainy season now extends into autumn, which is historically the mountain travel season.

Throughout this prolonged tail end of the rainy season, they have documented at least one episode of heavy precipitation nearly every year for the past decade, with mountain weather becoming more hazardous.

Recent Emergency on Everest

Last weekend, a sudden blizzard stranded several hundred of tourists near the east-facing face of Mount Everest for days in freezing conditions at an altitude of more than 16,000ft.

Approximately 600 trekkers were escorted to security by the end of that week, according to sources.

A single person had died from extreme cold and mountain sickness, but the others were reportedly in good health.

Similar Events Across the Region

This was on the Tibetan side but something similar had developed on the Nepal side, where a Korean climber died on Mera Peak.

The international community found out after some delay because communications were disrupted by torrential rains and heavy snowfall.

Officials calculate that landslides and sudden floods in the country have killed approximately sixty individuals over the previous week.

"It is highly unusual for autumn during which we anticipate the skies to remain clear," commented an experienced mountain guide.

Economic Impact

Considering this is the preferred season, regular storms like this have "affected our trekking and mountaineering business," he added.

The monsoon season in northern India and Nepal usually continues from early summer to mid-September, but no longer.

"Research shows that most of the annual cycles in the previous decade have had monsoons continuing until the second week of October, which is certainly a shift," said a high-ranking weather expert.

Growing Weather Severity

Even more worrying is the heavy precipitation and snow the concluding phase of the period produces, like it did recently on 4 and 5 October.

At elevation in the mountain range, such extreme weather translates to blizzards and snowstorms, which constitutes a huge risk for hiking, mountaineering and the travel industry.

Firsthand Accounts

Exactly what occurred last weekend when the conditions shifted very abruptly - the winds began howling, temperatures dropped sharply and visibility decreased significantly.

The trail that had comfortably led the hikers to what was expected to be a breathtaking resting point was now buried in white accumulation and extremely difficult to navigate.

Still, one hiker, who had climbed these mountains more than a dozen times, said he had "never experienced weather like this" before.

Expert Analysis

A primary major driver is the increased amount of moisture in the air because of how the planet has been warming, scientists say.

This has contributed to heavy precipitation over a short span of time, often after a prolonged period without rain – in contrast to in the past when monsoon showers were distributed evenly over the entire season.

A Intensified Monsoon

Weather experts say the monsoons in South Asia at times seem to have become more intense because they are increasingly interacting with another atmospheric phenomenon, the westerly disturbance.

This is a atmospheric depression that originates in the Mediterranean region and travels east - it transports cold air that brings rains and sometimes snow to the subcontinent, neighboring countries and Nepal.

Climate Change Effects

Scientists have also discovered that in a heating planet, the growing interaction between western weather systems and seasonal rains is causing an additional unusual result.

The hotter atmosphere is forcing the weather systems higher, which means these atmospheric conditions are now capable to cross the Himalayas and affect the Tibetan plateau and other regions that did not see so much precipitation in the past.

"What's changed is the predictability of patterns; we cannot presume that conditions will occur the identical from year to year," said an seasoned expedition leader.

"That means flexible planning, real-time choices, and experienced leadership [in the Himalayas] have become even more important."