Nepal, the Himalayan country is the best destination for the tourism activities throughout the year, however; there are four distinct trekking seasons in Nepal. Each season has its distinctive attractions to offer. The seasons can be classified as follows:
Autumn (Sept. - Nov.)
Autumn is the best time to experience the trekking in the Himalayas, which offers an excellent weather and exhilarating mountain views and one can experience the festival and culture of Nepal as the biggest festival of Nepal fall in this season, such as Dashain and Tihar (Deewali) which occur in October and November.
Winter (Dec. - Feb.):
Winter season is noted for occasional snowfall only at higher elevations. Hence it is ideal for trekking at lower elevation, generally below 3000 meters and it is good time for the having adventure activities such as mountain bike, Bungee Jumping, cycling tour, paragliding, river adventure and jungle Safari.
Spring (Mar. - May):
Different varieties of wild flowers, most exceptionally the rhododendrons, make the hillside above 3000 meters a haunting paradise during this season. It is mildly warm at lower elevations, and at higher elevations over 4000 meters, the mountain views are excellent and temperature is quite moderate. This season is the best time to have the mountain expedition, peak climbing, trekking and hiking in Nepal.
Summer (June - Aug.):
Summer season which represent the monsoon season in Nepal, as it rains almost every day during this season. So this season can be the best time for river adventure as the level of river in Nepal become higher. You also can have Agro tour as Nepalese farmer farm in their land in this period. This season also would be the best for those who are keen to know about the vegetation as a botanist as the higher valleys and meadows blossom with flowers and lush vegetation.
You can do most of the Nepal treks like Everest base camp or Annapurna Sanctuary on Autumn, Spring and Winter where as Upper Mustang trek is good even in Summer as it won't rain much there.
Note: - Beside these seasons you can discover this part of the world through Trekking, Rafting, and Jungle Safari, wild life safari, Hiking, mountain expedition, peak climbing, mountain flight, Bungee Jumping, mountain bike and cycling tour Paragliding all over the year.