The best time to visit Nepal depends on the purpose of your visit. October to November is the ideal time to travel as the weather is warm and clear sky offers mesmerising views of the Himalayas. Also most festivals fall in this duration which lets you celebrate and get insights to the culture.
Winter: Winter is great to hike low altitude trails and the right clothing should make it comfortable. You can also enjoy wildlife safari in winter for better sighting of animals.
Monsoon: Monsoons are not the best time to visit the mountain regions and you can miss out on scenic views due to cloudy sky.
Summer: The jungles can be extremely hot during the summer season. Trekkers prefer the months of March and April. Also, you get to enjoy the Holi festival.