Though Nepal falls on the regime of sub-tropical monsoon climate, actual climatic conditions vary from area to area depending mainly on topographic altitude. In general, temperature during both summer and winter months decrease from south towards north. However, low river basins of the mountain zone have warmer climate than adjacent higher areas. The prime source of rain is the summer monsoons blowing from southeast direction. The regional distribution of rainfall varies much from area to area depending on local topographic features and oceanic distance. In general, rain diminished from Pokhara Valley towards the west. The intra-Himalayan high basins located in Mustang, Dolpa and Manage Districts are the areas receiving least amount of rain (less than 50cm). On the other hand, there are several pockets in the hilly and mountainous zones of central and eastern Nepal where the total annual rainfall is exceptionally high (higher than 300cm). 

Since altitude is the guiding factor in the climate of Nepal, five different types of climate on the basis of topographic elevation have been recognised. These are -

1. Sub-tropical Monsoon Climate
2. Warm Temperate Climate
3. Cool. Temperate Climate
4. Alpine Climate
5. Tundra Climate.