Nepal's climate ranges from subtropical in the southern Terai plains to arctic conditions on the high Himalayan peaks, all within a north-to-south span of barely 200 km. Temperatures reach above 40°C (104°F) in the lowlands during the pre-monsoon heat and plunge below -40°C (-40°F) near the summit of Mount Everest. The best time to visit is October and November, when post-monsoon skies are clear and mountain views are at their sharpest.
Few countries pack such climatic variety into so little ground. As the land rises from near sea level to 8,849 metres at the top of Everest, it passes through five vertically stacked climate zones. A traveller can leave the steamy jungles of Chitwan in the morning and reach snowbound alpine passes by nightfall, experiencing tropical to arctic weather in a single day. For broader background, see our nepal country guide.
What Drives Nepal's Climate
Two forces shape Nepal's weather: altitude and the Indian monsoon. Because temperature falls roughly 6.5°C for every 1,000 metres of elevation gain, the country's climate is determined far more by height than by latitude. The result is a layered system: the Terai plains below 500 m are subtropical, the mid-hills between 500 and 2,000 m (including the Kathmandu Valley) are warm temperate, the highlands from 2,000 to 3,000 m are cool temperate, and alpine then arctic conditions dominate above 3,000 m. Under the Köppen system, Nepal includes Cwa, Cwb, Dwb, ET and EF zones.
The Himalayas also act as a vast wall. They block moist air moving north, wringing out heavy rain on the southern slopes while leaving the Tibetan side bone-dry. This rain-shadow effect explains why some trans-Himalayan valleys receive less rainfall than a desert.
The Four Seasons
Nepal experiences four broad seasons, each with a distinct character:
- Spring (March–May): Warming days of 10–30°C, with hillsides ablaze in rhododendron blossom. Lower elevations grow hazy.
- Monsoon (June–September): Hot and humid, 20–33°C, with frequent downpours. Landscapes turn lush green but trails grow muddy and leech-prone.
- Autumn (October–November): The clearest, most stable weather of the year, with comfortable 7–25°C days and crisp mountain visibility.
- Winter (December–February): Cold, dry and often clear, with nights dropping to -2°C in Kathmandu and far lower at altitude. Many high passes close under snow.
In the Kathmandu Valley the average annual temperature hovers around 19°C, with about 2,100 hours of sunshine a year. The Terai, by contrast, shares the climate of northern India, where pre-monsoon temperatures can climb past 40°C.
Rainfall and the Monsoon
The monsoon is the single most important weather event of the Nepali year. Arriving from the southeast in early June and retreating by late September, it delivers roughly 80% of the country's annual rainfall in just four months. Nationwide totals range from about 1,500 to 2,500 mm, but distribution is wildly uneven.
Pokhara, sitting directly beneath the Annapurna range, is one of the wettest cities in Asia, soaking up as much as 3,500 mm a year as monsoon clouds pile against the mountains. Step behind the main Himalayan ridge, however, and the picture flips entirely. Rain-shadow regions such as Upper Mustang and Dolpo are high-altitude semi-deserts receiving under 200 mm annually — drier than many parts of the Sahara's fringe. Because of this, these trans-Himalayan valleys remain trekkable even during the monsoon, when the rest of the country is awash.
Climate Extremes
The vertical compression of Nepal's geography produces remarkable extremes side by side. While farmers in the Terai endure 45°C heat before the rains break, climbers high on Everest face summit temperatures that can feel like -60°C once wind chill is added. Winter occasionally brings western disturbances that dust the higher elevations with snow, and treks like Everest Base Camp routinely see -20°C nights in the cold months.
This same gradient gives Nepal extraordinary biodiversity, from tropical sal forests and one-horned rhinos in the south to snow leopards and blue sheep in the alpine north — all sustained by the country's stacked climate belts.
When to Go
Timing matters enormously here. The headline recommendations:
- Trekking (Everest, Annapurna): October–November and March–May.
- Kathmandu and cultural sites: October–March.
- Jungle safari in Chitwan or Bardia: October–March, when wildlife gathers at shrinking water sources.
- White-water rafting: October–November, when rivers run high but skies are clear.
Autumn (October–November) is the undisputed peak season: post-monsoon air is washed clean, temperatures are mild, and the high peaks stand out in sharp relief. The trails are busier as a result. Spring is the strong runner-up, prized for warmer days and rhododendron colour, though lingering haze can soften lower-elevation views. The monsoon and deep winter are best left to specialists — desert treks for the former, well-prepared high-altitude expeditions for the latter.
Frequently Asked Questions
What is the best month to visit Nepal?
October is generally considered the single best month. The monsoon has cleared, skies are crisp, mountain visibility is excellent, and daytime temperatures are comfortable for both trekking and sightseeing.
How cold does it get in Kathmandu in winter?
Kathmandu winters are cool rather than freezing during the day, but nights in December and January regularly fall to around 2°C, occasionally dipping below zero. Days remain dry and often sunny.
Can you trek in Nepal during the monsoon?
Yes, but choose carefully. Most popular trails are wet, slippery and leech-ridden from June to September. The rain-shadow regions of Upper Mustang and Dolpo, however, stay dry and are ideal monsoon-season alternatives.
How many climate zones does Nepal have?
Nepal has five vertically stacked climate zones, ranging from subtropical in the Terai lowlands to arctic on the highest Himalayan summits, all compressed within roughly 200 km from south to north.
