The Climate of Nepal is dependent on altitude variation (ranges from 75m to and 8,848.86m above sea level) and Geographical features. As in the western world, there are four seasons in Nepal: Spring, Summer, Autumn, and winter. Six Seasons are in Nepal, additionally early summer and Early Autumn in western seasons.
Here are short descriptions of four seasons in Nepal.
Spring Season (March-May)
The Spring season is also called the Pre-Monsoon season that starts in March and lasts till May in Nepal. It brings the warm weather.
The Spring season is considered the best time for trekking in Nepal. An extensive variety of flowers like Rhododendrons (National Flower of Nepal) and Magnolia blossoms in different parts of the country. The spring season in Nepal is neither too cold nor too hot. There is low precipitation in spring, the trail is easily trekkable, and there is minimum possibility of sudden accidents.
Summer Season (June-August)
The summer season is the monsoon season in Nepal that starts in June and lasts till August. It rains daily and thunderstorms sometimes during the summer season. The Hilly and Terai experience the higher temperature. The average temperature all over Nepal lies between 20℃ to 35℃.
Lush green vegetation surrounds most of the hills in the summer season that gives a beautiful view. Mist, rain, and fog occur daily in this season. In summer, snow melts in the Himalayas. The trekking trails in most areas are slippery, so there is a high chance of unfortunate accidents. You can travel with precautions in this season.
Autumn Season (September- November)
Autumn Season is also called Post Monsoon, starts from September and lasts till November.
The Autumn season attracts many tourists every year in Nepal. Cool and refreshing weather in autumn makes it the perfect time to visit. The southern part is with a dry and mild climate, clear weather in autumn. The Northern region is not extremely cold and is perfect to trek. The average temperature in the altitude ranges between 1,000 to 3,500meters, is 20℃ at day and 5℃ at night. At higher altitudes, the temperature drops to around 0℃.
The deciduous trees change their color from green to yellow or orange. The vibrant colors are present in the trekking trails during autumn that looks cheerful. The autumn season is the season of festivals because the Main Festivals in Nepal: Dashain, Tihar, and the Chaat festival, are celebrated. Autumn is the rice harvesting season, which gives gorgeous views.
Winter Season (December- February)
The Winter season in Nepal starts in December and lasts till February. The days are clear with sunny weather and cold. The higher altitudes temperature lowers below 0℃ that experiences the occasional snowfall. Thorong-La Pass in the Annapurna region, Gosaikunda pass, Khongmola pass, and Lauribina pass are the higher altitude passes in Nepal that get severe cold in winter.
Wintertime is perfect to see the clear and beautiful views of the scenery. It is the best trekking time for those who love to walk in the snow. Winter is famous for many short and easy treks in Nepal.
Rainfall in Nepal
About 80% of rainfall in Nepal occurs during monsoon time. It rarely rains in winter and is more marked in the Western Hills. Lumle, just 25miles from Pokhara, receives the highest rainfall in Nepal that is more than 5000mm/year, which is more than the Tourism city Pokhara which receives only around 3500mm/year rainfall. Mustang is also called desert of Nepal, lies in rain shadow-behind stays dry the whole year. Mustang gets an average rainfall below 300mm in a year, which is the lowest rainfall data in all over Nepal.
Geographical zones of Nepal:
The Plain (The Terai)
The Terai region lies in the Southern part of Nepal, altitude ranges from 75m to 300m, and experiences a tropical savanna climate type. In summer, the days are hot (exceeds 37℃ and 45℃ in some places). In winter, the days are sunny and warm but cool at night, or cold often sometimes. The average temperature in January and April are 15℃ and 40℃, respectively.
Chitwan National Park is also called the Hub for exotic animals in Nepal, lies in the Terai region of Nepal. The summer minimum temperature is 23℃ and the maximum about 35℃. The winter minimum temperature is about 7℃, and the maximum temperature is about 23℃.
The Hilly region
The Hilly Region lies in the middle between Terai and The Himalayas and constitutes the Mahabharat and Chure Hills. The hilly region altitude ranges from 600m to 4,877m, the mild temperature during summer (ranges from 20℃ to 35℃) and cold in winter ( ranges from 2℃ to -4℃). The average temperature in January and July are 13.5℃ and 26℃, respectively.
Kathmandu valley lies at the elevation range of 1200m to 2300m above sea level in the Hilly Region. The hills in Kathmandu valley are within the deciduous monsoon forest zone. The cultural capital of Nepal in the warm temperate zone has favorable weather all around the year. The average temperature of January is 11℃ (51.5℉), the days are sunnier and mild, while the night gets cold.
Pokhara city is also famous as a tourism city in Nepal. It lies at an altitude ranging from 837m to 1,740m and has a humid subtropical climate. The average temperature in summer ranges from 25℃ to 35℃, and in winter ranges from -2℃ to 15℃. The skies are generally clear and sunny in winter and spring. Pokhara valley does not receive snowfall but its surrounding hills observed snowfall occasionally in the higher zone. The precipitation occurs high in the monsoon here.
The Himalayan Region
The mountain region lies in the Northern part, subalpine and alpine zone, with great altitude ranges from 3,000m and 8,848.86m (The altitude range of the highest peak in the world: Mt. Everest). The temperature falls by 0.2℃ to 1.2℃ with the rise in 100m altitudes. The climate ranges widely in the Himalayan region, humid subtropical in the lower zone, cold and dry desert conditions on the Northern side. On the south-western side of the higher mountains, heavy rainfall occurs in the monsoon. The northern - western side of the Himalayan region has a cold and dry climate. Snow falls in the form of precipitation in the late winter and spring months.
There is a great variety of soil, climates, altitude, and rainfall in this region. The floral and faunal species in this region are dependent on their variation.
At the higher elevation of mountains, permanently ice and snow are present. Well exposed areas receive heavy rainfall but the leeward side receives less rain. Upper Mustang and Manang are sheltered from the Monsoon rains and receive the lowest annual rainfall in Nepal.
Namche is also renowned as the gateway to Everest Trek, lies at the elevation of 3,440m, has warm summer and cold winter. The average minimum temperature in winter is -8℃, and the maximum temperature in summer is 16℃. The floral and faunal species in this region varies with the climate, soils, rainfall, and climate. It receives an average precipitation of 1110mm/year and a temperature of 6.1℃.
Everest Base Camp region receives an average precipitation of about 18 inches and is justly dry. The lowest temperature is about -17℃ at night, which occurs mainly between Mid-December to End of January. Temperature increases with the start of the spring season. Warm temperatures on sunny days and nights get cold in spring. Despite the cold, the views of the snow-capped mountains and surrounding valleys from Base Camp look impressive in winter.
The average temperature in autumn is about 15℃. The spring temperature is mild that it is hot on days and cool nights. The average temperature during the day during spring is 25℃. At night, the Temperature can get around -15℃ in spring.
Annapurna Base Camp summer's highest temperature is about 19℃, and the lowest temperature is about 4℃. The autumn temperature ranges between 20°C to -10℃. The Winter season gets cold. That temperature lowers about -20℃ in mid-winter time and a maximum of about 9.3℃.
Traveling in Nepal is doable all around the year. Each season has different beautiful features that provide different trekking experiences. Even in winter, the temperature gets very low in higher altitude zones but offers stunning and clear views. Spring and autumn seasons are the best time to visit. Spring and autumn offer good weather and beautiful features for traveling. Spring has a warm temperature and is the flower blooming season in Nepal, Rhododendrons (in Upper regions), and various wild-flower blossoms in different parts of the country. Autumn offers the refreshing weather of the environment.
For more information about the climate of Nepal, you can visit the official page of the Government of Nepal: http://www.dhm.gov.np.