This is the famous Annapurna region, which attracts large numbers of hikers. Walking routes are readily accessible, the paths are well maintained and there are numerous routes offering fantastic views. The Mustang soil is arid, even desert like in places, and is sheltered from the rain by the Annapurna mountains. You can therefore go in summer, if you're lucky, despite the monsoon! Spring and autumn remain the best times to visit and are recommended for hikers, so as to avoid the cold temperatures at high altitudes.
Avoid at all costs visiting Katmandu in the months of May and June. The heat is unbearable and the roads are muddy! Visiting the capital is fantastic but quickly becomes exhausting, so avoid the difficult weather conditions that occur in high summer. Choose to visit the country's largest town in spring or autumn if possible. You could also go in winter. It's not as if you are hiking at high altitude, so the temperatures are pretty much bearable in December and January.
The most easterly region of Nepal is home to Kachenjunga, the third highest mountain in the world. The natural environment is unspoiled and absolutely exquisite. The long path leading to the base camp at Kachenjunga passes through beautiful countryside, with waterfalls, lush vegetation and countless species of plants. The monsoon here is very heavy and best avoided. You should also avoid winter if you are planning to climb Kachenjunga, because it's bitterly cold. The best time to go, as for the rest of the country, is in mid-season.
In autumn, the sky is clear and the temperatures are comfortable. Take advantage of this if you want to make a dream come true and go to Mount Everest or Annapurna! Nepal is in fact home to ten of the highest peaks in the world and is an exceptional playground for daring hikers. These spectacular mountains are usually climbed in autumn, or in the spring, when the weather is best for the ascent. On the contrary, the period from June to September is to be avoided, since the monsoon makes the ground slippery and the views are marred by the clouds. You even risk coming across leeches! In December and January, the temperatures are too low to appreciate the climb as much as in mid-season.
This is the lake Rara region, home to a huge number of bird species. Lake Rara is the largest lake in Nepal and is worth the trip. There are lots of temples to visit here and you can also join the Great Himalaya Trail. It's an absolutely perfect area for nature lovers. Choose spring and autumn to visit this region, as for the rest of the country. Luckily this area rarely experiences the monsoon, so you can go in summer, though there is still a possibility of rain. The land is dry, very little of it is cultivated and the population is of Tibetan origin.
Go to experience the Nepalese wildlife in the Far West of the country. Here you might come across leopards, monkeys, bears and birds during a really authentic trekking experience. Go via the medieval villages and learn about the history of the Malla dynasty, dating from the 12th to 14th centuries. The ideal time to visit is in autumn or spring but winter is also a possibility if you're not planning to go into the mountains. Avoid the months of June to September, as for the rest of the country, although an exception can be made if you want to visit the Khaptad Festival, which takes place in August or September and attracts large numbers of pilgrims.