Nepal has a typical monsoon two - season a year.
There is a dry season from October to May and there
is the wet season, the monsoon, from June to
September. September - November, the start of the
dry season, is in many ways the best time of the
year in Nepal. When monsoon just ends, the
countryside is green and lush. Nepal is at its most
beautiful and during this season there are plenty of
colorful festivals to enjoy. Nepal’s weather is
generally predictable and pleasant. There are four
climatic seasons: March–May (Spring), June–August
(Summer), September–November (Autumn) and
December–February (Winter). The monsoon is
approximately from the end of June to the middle of
September. About 80 per cent of the rainfalls during
that 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 28ºC (83ºF) in the
hill regions to more than 40ºC (104ºF) in the Terai.
In winter, average maximum and minimum temperatures
in the Terai range from a brisk 7ºC (45ºF) to a mild
23ºC (74ºF). The central valleys experience a
minimum temperature often falling bellow freezing
point and a chilly 12ºC (54ºF) maximum. Much colder
temperatures prevail at higher elevations. The
Kathmandu Valley, at an altitude of 1310m (4297ft),
has a mild climate, ranging from 19-27ºC (67-81ºF)
in summer, and 2-20ºC (36-68ºF) in winter.