Climatic factors are very important in deciding when to visit Nepal.
October-November,the start of the dry season, is in many ways the best time of a year: the weather is balmy, the air is clean, visibility is perfect, and the country is lush following the monsoon.
February-April,the tail end of the dry season is the second-best period: visibility is not so good because of dust, but the weather is warm and many of Nepal’s wonderful wild flowers are in bloom.
In December and January,the climate and visibility are good but it can be chilly: trekkers need to be well prepared for snow, and budget hotels in Kathmandu – where heating is non-existent – can be gloomy in the evening.
May and early June are generally too hot and dusty for comfort, and the monsoon from mid-June to September obscures the mountains in cloud and turns trails and roads to mud.