Trekking around various regions of Nepal is possible all throughout the year, however best times to go for trekking in Nepal are during two seasons: in autumn season during the months of September, October, November and in spring season during the months of March, April and May. Both of these times are most recommended and favorable seasons for trekking in Nepal as you can get the most out of your adventure in terms of scenic unobstructed views, avoid heavy rainfall, warm days and perfect weather just as you wished to be in. As these are the best seasons, it is also the peak trekking season in Nepal when thousands of tourists visit Nepal to fulfill their desire of trekking around Himalayas. Therefore expect crowd at busy trails around Everest, and Annapurna regions.
On the other hand, trekking in Nepal during monsoon season during months of June, July and August rewards you with greenery, lush vegetation, blossoming flowers at valleys, mountains and more like jungle adventure at the cost of more chances of heavy rain, cloudy Himalayan views, muddy and slippery trails with leeches around. However, it is the best time if you love plants and doing some botanical research in Nepal. Another important thing to consider while trekking in Nepal during monsoon season is that Nepal has trans-Himalayan regions such as Mustang and Dolpo (Upper Mustang, Lower Mustang, Upper Dolpo, Lower Dolpo). These regions lie in rain shadow area and receive very less rainfall as the cloud flowing from the south is blocked by the Himalayan range. So, off the beaten path trekking can be organized in this area that lets you experience the authentic local lifestyle of local inhabitants living there.
Trekking in Nepal is also possible in winter season during the months of December, January and February however snowfall and cold temperature avoids you to for high altitude treks. Also Christmas holidays lies in this winter season, when you can go for our special Christmas trekking around low altitude treks like Ghorepani poonhill at Annapurna region; one of the happening place to be in Nepal during holidays.