From the lowlands close to the Indian border to the 8,850m peak of Mount Everest, Nepal's climate is hugely altitude dependent. The landscape divides into three quite distinct zones. The Terai zone, located in the south, runs along the border with India, with some areas virtually at sea level. A belt of often humid, jungle and farmland, the temperature in the Terai, for example in Janakpur, can often hit 35°C. It's home to two of the country's most impressive National Parks, Chitwan and Bardia, both of which are home to the rare one-horned rhino and iridescently colourful birdlife.
Seasons in Nepal can be divided roughly into four seasons, although (as with weather conditions worldwide) these seasons are increasingly blurred. Winter occurs from late November to February and is typically rain-free and clear. High altitude areas above 3,000 metres will be snowy and very cold indeed with night time temperatures of -10°C not uncommon. Whilst you won't want to venture towards Everest Base Camp, lower altitude treks are quite feasible at this time of year if you come properly prepared for the chill. Even in the Kathmandu valley and the flat plains it gets cold at night with temperatures hovering around 3°C so you should pack a warm fleece for the evenings. Winter is low season for tourists and a great time of year to visit places like Pokhara and the National Parks on the plains.