The two main trekking seasons are: Spring (3rd week in February to end 1st week in May) and Autumn (3rd week in September to early December). This applies to all trekking routes. The most popular trails such as Everest and the Annapurnas are very crowded in March-April and more so from mid October to the end of November.
During the Monsoon months, the weather in the rain shadow regions behind the High Himalaya is warm with flowers on alpine meadows. Mustang can be explored all year round, but is cold from mid December to 1st week in March. For Dolpo consider 2nd week in August to 1st week in October. Snow is likely from the 3rd week. In July. Flowers are abundant in the Langtang Valley β but cloud can limit mountain views.
During Winter (December to February), short treks in the lower southern regions, such as Poon Hill in the Annapurnas or Helambu north of Kathmandu can be cold at night, but very rewarding.
The Annapurna Sanctuary (Base Camp), Manaslu and Everest Base Camp treks are possible in winter: but will be very cold and the high passes can be tough. Our company offers a selection of treks that can be safely and enjoyably undertaken in every season.
How air pressure decreases with the altitude Graph
