Nepal has broadly temperate climate with four main seasons centered around summer monsoon. Climatic conditions of Nepal vary from one place to another in accordance with their geographical features. Summers in the north are cool and winters are extremely cold while in the south summers are tropical and winters are mild. Nepal has five seasons: spring, summer, monsoon, autumn and winter.
Winter (Dec-Feb): December to early February is relatively warm in the daytime and freezing at night. The trekking trials are found quieter and short and fantastic whitewater rafting. Winters are normally clear and stable. It never really snows in Kathmandu, while in the Himalayan region it snows heavily. Trekking to nearer Himalayan areas like Ghorepani, Poonhill could be fun during winter as you get to experience snowfall on the way. You can also trek to Annapurna Base Camp during this season. This is the best time to visit the plains of Nepal and explore Janaki temple, Lumbini (birth place of Gautam Buddha), Chitwan and others. You can spend a great time in Chitwan doing Jungle Safaris and attend the local Tharu community’s cultural programs.
Spring (March to May): Spring is the second tourist season. It has warmer weather and longer days. Trees and bushes that lost their leaves over the winter begin to grow new leaves again and also flower in spring. Spring is the best time to visit for viewing wildlife – despite the increasing heat. It is a beautiful time to go trekking as the flowers will have started to bloom in the mountains. Marchand is a lovely time to explore Nepal as rhododendrons bloom in the Himalayas.
Summer/Monsoon (June-mid September): There are some treks that are particularly good during summer and monsoon season as they lie in the rain shadow. Annapurna Circuit, Manaslu trek, Upper Mustang trek, and the Nar Phu Valley Trek. The famous Everest Base Camp trek can also be done during the monsoon season, but it could rain. The weather will get better day-by-day. A drawback during trek in monsoon is that you will have to deal with leeches. An advantage of having the monsoon season is crowd-free experiences. You’ll also be able to get good rates at normally busy destinations such as Chitwan, Pokhara and Bandipur. Marsyangai Valley and Tilicho. You can experience their lush greenery views.
Autumn (mid-Sept. to November): Autumn is the best season for witnessing the breathtaking Himalayas as well as terrific natural setting in Nepal. Fresh air and clear skies are the main reasons why October to November is the best time to visit Nepal. Views during this period are scenic, so trekking is perfect. It will be a dream come true experience. Visitors choose autumn since the views of mountains as well as surroundings are clear. You can also experience the main festival of the Hindus i.e. Dashain (festival of victory) and Tihar (festival of lights) during this season.