Nepal contains some of the most dramatic climate variation on Earth, ranging from tropical heat in its southern plains to permanent arctic conditions on Himalayan peaks, all packed into a country roughly the size of Arkansas. Average temperatures drop about 6°C for every 1,000 meters you gain in altitude, which means you can experience sweltering 45°C heat and subzero cold within the same country on the same day. The monsoon, arriving between June and September, delivers roughly 80% of Nepal’s annual rainfall and shapes nearly every aspect of life.
Five Climate Zones Stacked by Elevation
Nepal’s climate is best understood as a series of horizontal bands, each defined by altitude. The lowest is the Terai, a flat tropical belt in the south sitting between 60 and 330 meters above sea level. Tropical forests (many now cleared for agriculture) once dominated this landscape. Summers here regularly exceed 40°C and can push past 45°C in some areas, while winters are mild, ranging from 7°C to 23°C. If you picture the hot, humid lowlands of northern India, the Terai feels much the same.
Rising abruptly from the Terai are the Siwalik Hills, climbing from about 120 meters to nearly 1,800 meters. These hills are dry for most of the year and sparsely populated because of water scarcity outside the monsoon months. Above them sits the middle hills zone, home to the Kathmandu Valley and Pokhara, where the climate is temperate and the most comfortable for most visitors. Kathmandu averages summer highs around 28°C and winter lows near 3°C. Pokhara is slightly warmer and significantly wetter.
Higher still are the high mountain valleys between roughly 2,000 and 4,500 meters, including areas like Upper Mustang and the upper Kaligandaki. These valleys sit in the rain shadow of the Himalayan peaks, making them barren and arid despite their altitude. The high Himalaya blocks monsoon moisture from pushing north, so the landscape here looks more like Tibet than the lush green hills below. Above about 4,500 meters, you enter alpine and then arctic desert conditions. The permanent snow line sits between 4,500 and 6,000 meters depending on local precipitation, and everything above 6,000 meters is essentially frozen year-round.
The Four Seasons
Nepal’s year divides into four seasons, though the monsoon dominates the calendar. Spring (March through May) brings warming temperatures and blooming rhododendrons across the mid-hills. It’s one of the two peak seasons for trekking. Summer (June through September) is monsoon season: heavy, persistent rain that swells rivers, triggers landslides, and makes many mountain trails impassable. The Terai floods regularly. Pokhara receives nearly 830 mm of rain during these months alone, compared to just 26 mm in winter.
Autumn (October and November) is widely considered the best time to visit Nepal. The monsoon has washed the air clean, skies are the clearest they’ll be all year, and temperatures in the mid-hills are comfortable. Winter (December through February) is dry and cold. Kathmandu can drop to 2°C or 3°C at night, and higher elevations become bitterly cold, with mountainous regions plunging well below zero. Snow closes high passes, and many trekking routes above 4,000 meters shut down.
How Climate Differs Across Popular Destinations
The three most-visited areas in Nepal illustrate how much conditions vary even at relatively similar latitudes. Kathmandu, at about 1,400 meters, has peak summer temperatures around 28°C with monsoon rainfall of about 312 mm. Winters are cool and dry, averaging highs of 19°C and lows around 3°C with very little rain (about 15 mm over the three winter months). The valley can feel chilly and hazy in January but is pleasant most of the year.
Pokhara sits at roughly 800 meters and is noticeably wetter. Its position at the foot of the Annapurna range means it catches enormous amounts of monsoon moisture, nearly 830 mm over the summer months. Summer highs reach about 30°C. In winter, Pokhara stays mild with highs around 20°C and lows near 8°C.
Chitwan, in the Terai lowlands, is the hottest of the three. Summer highs hit 33°C with lows that barely dip below 25°C, making nights sticky and warm. Even winter feels warm by most standards, with daytime highs around 24°C. Rainfall during the monsoon sits around 404 mm, less than Pokhara but still substantial enough to make the national park lush and green through autumn.
The Rain Shadow Effect
One of Nepal’s most striking climate features is the rain shadow behind the Himalayan wall. The summer monsoon pushes moist air northward from the Bay of Bengal, and the Terai and mid-hills receive the bulk of that moisture. But the high peaks act as a barrier. Regions on the north side, like Upper Mustang, the Dolpo area, and the Tibetan marginal mountains above 6,000 meters, are startlingly dry. These landscapes look almost desert-like: stark, eroded crags with little vegetation. Travelers who visit both the lush Annapurna foothills and the arid upper Kaligandaki valley in a single trek often describe the transition as walking from one country into another.
Climate Change in the Himalayas
Nepal’s climate is shifting in measurable ways. Glacier and snow cover in the central Himalaya has already declined by about 1.7%, and projections suggest a further loss of 4.7% to 4.9% by 2050 under moderate and high emissions scenarios. Water bodies have also shrunk by about 2%. At the same time, forests are expanding upslope into areas that were previously too cold to support tree growth, projected to increase by over 4% by mid-century.
For a country where farming depends heavily on monsoon timing and snowmelt, these changes carry real consequences. While overall monsoon rainfall hasn’t shown a simple increase or decrease, extreme rainfall variation has intensified, and that volatility hurts crop productivity, particularly for rice, Nepal’s staple grain. Erratic monsoons mean some years bring flooding and landslides while others bring drought to the same regions. Glacial retreat also threatens the long-term water supply for rivers that millions of people depend on for drinking water, irrigation, and hydropower.
Settlements that once topped out at about 3,900 meters are now being established higher, partly to serve trekkers and mountaineers. Villages like Gokyo sit at 4,790 meters, in zones that were traditionally used only as seasonal camps. As temperatures warm and snow lines recede, the livable and farmable bands of Nepal are gradually creeping upward.