When it comes to trekking in Nepal, one can do it all year long, excluding adverse weather. However, if we take High Himalayas in consideration, extreme winter lasting from early December to February is near impossible. Other than that, you can select any time of the year to head out for a sound trekking. March to May (spring) and mid-September to November (autumn) is an ideal time for witnessing the experience of true trekking in the Himalayas. Similarly, if you can overlap your treks to one of the many local festivals of your trek regions, you can get bonus experience of knowing the culture and traditions of the people living in these areas.