Now, trekking season in Nepal does not follow the traditional trekking calendar. Global average temperature is rising by 0.18 degree Celsius per decade but Himalayas temperature is rising by 0.28 degree Celsius per decade. Global warming has tended the Himalayas to warm faster than the global average. According to the scientists, this phenomenon is called “elevation-dependent warming“. It means when we go higher in the mountain there is increment in the rate of warming. Since 1950, Himalayas are warming 50% faster than global average.
Why Himalayas warm faster than global average?
The White Mirror Effect
As we know, snow and ice of the Himalayas reflect most of the sunlight back into space but global warming melts snow of the Himalayas. As a result, it exposes dark ground which absorb more heat. When this cycle continues, it melts more snow and expose more dark ground.
Himalayas have very high elevation
The Himalayas have very high elevation that they are very closer to sun’s energy. There is thinner air in the higher altitude which cannot hold heat well. So, this is also the one of the reasons that Himalayas warm faster than global average.
Pollutions trapped from lowland area
Wind carry pollution from lowland area’s (India’s city and factories) towards the Himalayas. This pollution forms a dark particle and settles on the snow which allows to absorb more sunlight and melt faster.
Effects of rising temperature in the Himalayas
As we know, Himalayas of Nepal are warming 0.28°C per decade. Some parts of Nepal are warming much faster which have led to following effects:
The August 2024 glacial flood: Thame village destroyed
On August 16, 2024, the village of Thame was hit by 22-meter-high wave. It was nearly erased from the map by glacial flood triggered by permafrost thaw. Thame village is a Sherpa village which lies on the elevation at 3800 meters in the Everest Region. It is the most popular stop on the way to Everest Base Camp and Gokyo Lakes routes. It is the birth place of famous mountaineers such as Tenzing Norgay and Apa Sherpa.
Since 1950, the Himalayas of Nepal have warmed by about 2 degrees Celsius in total. Because of this phenomenon, permafrost begin to thaw. Scientifically, it exists only when temperatures stay below 0°C. Even if it’s still technically below freezing, when the average temperature rises then it starts to thaw.
Permafrost is a frozen ground which acts as a glue that hold mountainside together and soil is hold together by ice. When permafrost begin to thaw, rocks can move, shift and fall, soils become loose and slippery and also mountainside becomes unstable. This phenomenon has led to rock avalanche which crashed directly into glacial lake that was high in the mountains at an elevation of 4,900 meters. This event broke lake’s natural dam, 156,000 cubic meters of water was released approximately. Then, water fell from 120 meters height which crashed to another lake and as a result broke another lake’s dam too.
Similarly, another lake released 303,000 cubic meters of water. Due to this phenomenon, water become slurry and when it fell downhill, it picks up rocks, mud, ice chunk, trees and anything in its way. Then this mixture of water, ice, rock and mud built a wall of destruction. As a result, a 22-meter wave hit Thame village. This devastating Glacial Lake Outburst Flood (GLOF) destroyed more than 20 houses, a school, clinic, teahouses and monasteries.
The October 2025 Disaster: Deadly blizzard hit Everest Region
Global warming has risen the temperature of Indian Ocean and Bay of Bengal approximately by 1 degree Celsius and 0.5 degree Celsius respectively since 1950. As we know, in Nepal monsoon comes Bay of Bengal. Most of the heat is observed by the ocean which tends to evaporate faster. As a result, Indian Ocean and Bay of Bengal are creating more moisture in the air. This moisture is shifted north towards the Himalayas. According to the science, for every 1°C of warming, the atmosphere can hold 7% more moisture. Since, Himalayas have warmed by 2 degrees Celsius from 1950 so there is 14% more moisture in the air.
Moisture acts a fuel for storm. With 14% more moisture in the air gives 14% extra fuel to storm. This phenomenon leads to more intense and unpredictable monsoon. Previously, monsoon used to end in mid-September but now it lasts till second week of October. Now, Westerly Disturbances arrive in between October and November from the Mediterranean. Since, monsoon stays longer so it collides with westerly air over the Himalayas. This phenomenon has created deadly blizzard in the Everest Region on early October 2025.
Snow to Rain Shift: Caused the February Haze Problem
As we know, the Himalayas of Nepal have warmed by about 2 degrees Celsius in total which has led to rise in temperature above 0 degree Celsius during winter. This process of rising temperature takes place first at lower elevation. The precipitation falls as snow when temperatures are below freezing and it falls as rain when temperatures are above freezing. Previously, winter precipitation that used to be snow but now it is falling as rain in the lower elevation. This phenomenon is called “snow-to-rain shift”.
Nepal has already loosed 40% of snow according to research. In 1990, snow and ice covered 26,800 km² but now they covered only 16,300 km² of Nepal according to measurements from 2018. Due to this phenomenon, lower elevation became bare and dry. Previously, lower elevation used to have snow blanket all winter which protect the ground. As of now, there is no snow and soil is exposed to wind and sun then ultimately ground becomes dry.
Popular trekking routes like trails to Ghorepani Poon Hill and Nagarkot viewpoint have become dry and view of Himalayas are not seen clearly due to haze. Haze is formed due to rise in dust in the atmosphere and the source of dust is dry ground. February and march are the seasons when farmer do preparation for planting. During this time, farmers burn old crops which creates smokes and rise into atmosphere. This phenomenon also contributes to form blanket of snow covering the all-Himalayan foothill. Dust from dry ground and Smoke from farm fires form the thick haze that trekker see in the month of February.
December as Favorable trekking season
Previously, December was not considered as the favorable season for trekking. It was considered too cold and too snowy for trekking and the trekker used to avoid this season. As global warming has led to floods, blizzards, haze but it has reshaped new trekking season also which is December. Since, monsoon ends in mid-October so by December almost all moisture is vanished from atmosphere. Dust from bare ground and farm fires is not accumulated yet in the atmosphere. Although the December is cold but it has become one of the clearest and most feasible months to see the panoramic views of snowcapped mountains. During this month, trails are clear and feasible for walking and teahouses along the trails are also open.
Frequently Asked Question
Is December favorable for trekking in the Everest Region?
Yes, December is favorable for trekking in the Everest Region because weather is clear although it is cold. You can clearly view the Mount Everest along with other snowcapped mountains. In this month, trails of the Everest Region is also clear.
Why February is not feasible to trek Ghorepani Poon Hill?
Since, Himalayas of Nepal have already loosed 40% of snow due to which lower elevation became bare and dry. Wind easily pick up bare and dry soil then it is accumulated in the atmosphere. This phenomenon forms haze in the atmosphere. Due to haze, Himalayan range is not clearly visible from the Ghorepani Poon Hill viewpoint. So, due to this reason February is not feasible to trek Ghorepani Poon Hill.
Is late September favorable for trekking in the Everest Region?
Due to Global warming, monsoon stays till early October. Lingering clouds often cancel Lukla flights. So, late September is not favorable for trekking in the Everest Region.
