Nepal’s weather is generally predictable and pleasant and the climate varies considerably with elevation. There are four climatic seasons: March to May (spring) are good months for mountain treks, June to August (summer), September to November (autumn), while rain soaks the Terai and snow falls on the Himalayan peaks and December to February (winter) are prime mountaineering weather: the skies are clear and sunny, temperatures range from warm in the lowlands to crisp in the mountains.
The monsoon is approximately from the end of June to the middle of September, about 80 per cent of the rain falls during this period, so the remainder of the year is dry. Spring and autumn are the most pleasant seasons; winter temperatures drop to freezing with a high level of snowfall in the mountains. Summer and late spring temperatures range from 28 °C (83 °F) in the hill regions to more than 40 °C (104 °F) in the Terai.
In winter, average maximum and minimum temperatures in the Terai range from a brisk 7 °C (45 °F) to a mild 23 °C (74 °F). The central valleys experience a minimum temperature often falling bellow freezing point and a chilly 12 °C (54 °F) maximum. Much colder temperatures prevail at higher elevations. The Kathmandu Valley, at an altitude of 1310m, has a mild climate, ranging from 19-27 °C (67-81 °F) in summer, and 2-20 °C (36-68 °F) in winter.