Nepal's climate varies with its topography and altitude. It ranges from the tropical to the arctic. The lowland Terai region with its maximum altitude to approximately 305m, which lies in the tropical southern part of the country, for instance, has a hot and humid climate that can rise above 45 Degree Celsius (113 Degree Fahrenheit) during summer. The Midland regions are pleasant, almost all year round, although winter nights are cool. The northern mountain region, around an altitude above 3,300 m has an alpine climate with considerably lower temperatures in winter as can be expected. Almost all seasons are the best time to visit Nepal. Generally for the luxury tours and luxury trekking is the best way to experience in Nepal throughout the year.
1. September, October and November (Autumn Season in Nepal):
This is the best trekking season in Nepal which offers you excellent weather and wonderful mountain views. The weather is mild and perfect with no rain and scorching sun. The trekking trails will be full of trekkers. We can interact with the people of the world. During Autumn, Nepal is in a festive mood too. Nepalese observe two major festivals: Dashain and Tihar during Autumn. So, it will be stunning to travel in Nepal during Autumn.
2. March, April and May (Spring Season in Nepal):
The second premium trekking season in Nepal is Spring. The temperature is quite moderate, especially the rhododendrons (National flower of Nepal) are in complete blossom and the mountain views are excellent. An equal number of tourists visit Nepal and its mountains during Spring as in Autumn.
3. June, July and August (Summer Season in Nepal)):
This is the most preferable season to trek in the rain shadow areas like upper Mustang, around Annapurna, Upper Manag, Manaslu and Upper Dolpo etc. these regions are out of reach of the rain clouds because of the huge mountains, and unaffected by the monsoon. This season is also good for forest researchers and botanists, during this time for trek raincoat and insect repellents are strictly required. Actually, trekking in major regions like Everest, Annapurna, Langtang does not recommend. The heavy rainfall and landslides obstruct us to make a relaxed and comfortable trek during Summer.
4. December, January and February (Winter Season in Nepal)):
This is winter in Nepal will be cold for high mountain trekking but still a suitable time for trekking and hiking at lower altitudes normally below 3500 m. The temperature gets lower even below-10 in Everest, Annapurna, and Langtang region. Nepal's mountain receives heavy snowfall and avalanches during winter. So, you'd better not to make a decision to trek in Nepal's mountain during Winter.