Autumn: This is the best trekking season in Nepal and officering excellent weather and outstanding mountain views. The weather is very pleasant and clear and the mountain views are the best. Early October through to late November is the busiest period for trekking and all the guest houses are fully booked.
Spring: This is the second finest trekking season and less crowded on the trekking trail. The temperature is quite moderate; especially the rhododendrons are in complete blossom and the mountain views are excellent. The temperatures are mildly warm in the lowlands and little cold at higher altitudes and the sky is clear and the mountain views are best.
Summer: This is the most preferable season to trek in the rain shadow areas like Mustang, Upper Manang and Dolpo, Simikot. These places are out of reach of the rain clouds because of the huge mountains and are unaffected by the monsoon. This season is also recommended for forest researchers and botanist. Like wise Tibet high arid plateaus are ideal for summer trekking, The Annapurna regions Jomsom part also significantly less rain areas and short trek in this areas are recommended. The advantage of summer trekking is you will find the trekking trails and villages have few trekkers and you can enjoy the solitude and beauty of the mountains without any crowds.
