Both Weather and Temperature are critical when trekking. They directly influence the difficulty and also comfort of the journey. It’s essential to consider these factors carefully if you’re trekking in a remote part of Nepal like the Upper Mustang. Its unique location, lying in the rain shadow of the Himalayas, also makes its weather conditions unique. Each season here has distinct weather with distinct challenges and benefits. Knowing about the weather and temperature in Upper Mustang is also important when deciding on the itinerary and the packing list for the trek.
So, if you are planning an Upper Mustang trek, you should first know about its weather and temperature. You must be well-equipped and possess enough knowledge to enjoy the trek peacefully without any external hassle. And, weather doesn’t just mean temperature; you should also know about precipitation, wind speed, visibility, humidity, and more. This article will provide all the necessary information about the weather in Upper Mustang.
The Upper Mustang lies behind the Annapurna and Dhaulagiri ranges. Hence, the monsoon winds that travel toward Upper Mustang encounter these mountains and rise atop, resulting in rainfall on the windward side. The monsoon winds don’t have much moisture left in them, and when they travel toward Upper Mustang, they get compressed and absorb the moisture in the way. Hence, Upper Mustang becomes the rain shadow area and, as a result, receives minimal rainfall of about 252 mm with 63% humidity in one year. As a result, the region’s atmosphere is mostly dry, while regions like Everest and Annapurna get more rainfall and humidity.
Due to its lower elevation, the Upper Mustang typically experiences warmer daytime temperatures than the high-altitude trekking regions, such as Everest or Annapurna Base Camp. Winter temperatures here can drop significantly, especially at night, but comparatively, it’s nowhere near Everest Base Camp. For example, the lowest temperature in EBC (5,364 m) is -20°C but around -7°C in the Upper Mustang. Unlike other regions that experience heavier monsoon rainfall and colder winters, Upper Mustang has a more predictable dry season (October to April) and a milder wet season (May to September).
Among the 12 months, June stands out as the warmest month in Upper Mustang, with an average high of 24.8°C (76.6°F) and an average low of 16.5°C (61.7°F). June experiences consistently warm temperatures, signaling the onset of the summer season. In contrast, January is the coldest month, with an average high of 11.2°C (52.2°F) and an average low of 0.8°C (33.5°F).
The highest recorded temperature is around 35°C (95.3°F) in April and June. These months experience the hottest conditions, with April transitioning into the warmer season and June continuing the warmth through summer. The coldest temperatures occur in January, often dropping to -7.3°C (18.9°F) at night. The temperature in the regions like Choga La Pass (4,320 m) can even reach below -7°C. Hence, January typically sees the lowest temperatures, occasionally dipping well below freezing, signaling harsh winter conditions. Below is the monthly approximate temperature table of the Upper Mustang:
The chart below shows the varying temperature of the Upper Mustang throughout the year:
Temperature plays a significant role in determining the comfort and safety during the trek. For example, an extreme cold or hot temperature can make trekking uncomfortable. The risk of hypothermia, altitude sickness, and dehydration increases if you are trekking in extreme temperatures. Hence, many trekkers worldwide prefer moderate conditions when average temperatures are about 15°C to 20°C to make the trekking experience more pleasant and comfortable.
Since the Upper Mustang lies in the rain shadow area, its average yearly rainfall is relatively lower, around 252 mm. The wet season here spans from April to August, with precipitation peaking during July. The relative humidity is also higher during this time at around 85%. From September to February, the dry season dominates, with precipitation levels remaining much lower. Besides rainfall, snowfall is another type of precipitation that is dominant during the winter months of December to February.
June to August receive the heaviest rainfall, with June being the wettest month (392 mm or 15.44 inches), followed by July (865 mm or 34.06 inches) and August (673 mm or 26.51 inches). These months collectively account for a significant portion of the total annual precipitation. On the other hand, October marks the beginning of the dry season, with a sharp decrease in rainfall (67 mm or 2.64 inches). November (13 mm or 0.51 inches) and December (14 mm or 0.55 inches) are the driest months, with the relative humidity of 61% and 64% respectively. Below is the table of precipitation and humidity in Upper Mustang for each month.
| Month | Rainfall (mm) | Humidity (%) |
| January | 40 | 49 |
| February | 84 | 50 |
| March | 89 | 46 |
| April | 201 | 48 |
| May | 293 | 57 |
| June | 392 | 69 |
| July | 865 | 85 |
| August | 673 | 85 |
| September | 304 | 81 |
| October | 67 | 66 |
| November | 13 | 61 |
| December | 14 | 54 |
Many people do not prefer trekking when it is snowing or raining. Precipitation increases the risk and difficulty of the trek. Rain makes the trail slippery, making it more difficult to maintain proper footing. A wrong step in the wrong place might lead to life-threatening accidents. However, since Upper Mustang lies in the rain shadow area and receives lesser rainfall, it is trekable.
The number of sunshine hours is highest (about 13) in May, June, and July, suggesting that the Upper Mustang experiences relatively long sunshine during the warmer months. The months with the fewest sunshine hours are January, December, and November, each with about 8 hours of sunlight. To be precise, the sunshine hours vary from a low of 8.65 hours in January to a high of 13.78 hours in June, with a general range of about 5 to 6 hours between the maximum and minimum sunshine hours. Below is the chart showcasing the average sunshine hours in a day for each month.
Sunshine hours are crucial while determining the length of the trek. Longer hours mean more time to walk and rest while trekking. In contrast, fewer sunshine hours means you have less time to travel the same distance. Shorter days limit the trekking time and increase the risk of trekking in the dark, which is stressful and unsafe.
Autumn and spring offer great visibility in Upper Mustang. During these times, the skies are usually clear, providing unobstructed views of the surrounding mountains and landscapes. Summer and winter offer less visibility. Summer brings wind and monsoon clouds, resulting in obstructed views. Winter brings snowfall, which reduces visibility, especially at higher altitudes.
In addition to adventure, we trek in the Upper Mustang to witness the majestic Dhaulagiri and Annapurna ranges while closely observing the surrounding nature and landscape. Lesser visibility limits the scenic experience, blocks the trail, and makes navigation difficult. The best time to trek to the Upper Mustang for scenic beauty is in spring and autumn, as the skies are clear during these seasons.
The winds in Upper Mustang are stronger, about 10-20 km/h in May, June, and October, while February and August experience calmer conditions. The spring and the early summer are windy because of the seasonal transitions. However, the winter months, from December to Feburary, are characterized by lighter winds with speeds ranging from 2 km/h to 5 km/h.
Strong winds in high-altitude regions like Chogo La Pass can make trekking uncomfortable. The strong, chilly wind makes us feel cold and poses challenges like difficulty walking and maintaining balance. The gentle winds, however, enhance the trekking experience, soothing and relieving us during warmer days.
| Season | Record High °C (°F) | Average High °C (°F) | Average Low °C (°F) | Record Low °C (°F) | Precipitation mm (inches) | Humidity (%) | Sunshine Hours |
| Winter | 24 (75) | 13 (55) | 3 (37) | -7 (19) | 45 (2) | 51 | 9 |
| Spring | 35 (95) | 21 (70) | 11 (51) | -3 (26) | 194 (8) | 50 | 13 |
| Summer | 35 (95) | 24 (74) | 17 (62) | 11 (52) | 644 (25) | 80 | 13 |
| Autumn | 32 (90) | 20 (68) | 11 (51) | 1 (34) | 127 (5) | 69 | 10 |
Here are some of the tips that you might find helpful to prepare for Upper Mustang weather in your trek:
As a trekker, it is essential to consider the weather and temperature to understand the situation of the trail and ensure the right packing list. The weather conditions will help you determine how many gear to carry and what types of gear to carry for the trek. But, selecting the right gear and clothing for the Upper Mustang region trek can be tricky because of the weather conditions. Unlike other regions in the Himalayas, it falls in the rain shadow region and has an arid atmosphere. Considering this fact, below are a few of the season-wise items you shouldn’t miss:
In conclusion, the weather and temperature in Upper Mustang range from mild temperatures in the autumn and spring to the chillier nights in the winter season. The summer or the monsoon season here doesn’t receive as much rainfall as in the other trekking regions, providing the aird conditions. Remember that the more you ascend, the more unpredictable the weather can be; preparing for the trek is necessary. By planning for varying conditions, you can mitigate risks, choose the right gear, and find the best itinerary. Ultimately, being informed about Upper Mustang weather helps in maximizing safety and enjoyment during the trek.
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