Climatically, Nepal can be divided into three major regions.
1. Sub-tropical Plain
2. Hilly; and
3. Alpine with the Himalaya
1. The sub-tropical plain extends from east to west ranging from 300 m to 350 m. It bears sub-tropical monsoon climate. June, July and August are the wet months with heavy rainfall.
2. The hilly region with mid-land valleys ranging from 350 m to 3000 m has warm and cool temperate climate. The region also receives heavy rainfall in the months of June, July and August.
3. The Himalayan region from 3000 m to 5000 m has alpine climate and beyond in the high Himalaya area, tundra climate prevails.
The mid-hills, particularly, the Kathmandu valley & Pokhara valley, are pleasant with warm summers and cool winters. Mountain views are mostly clear from October till April except few days (in case of short showers). Although the mornings are foggy, the days are mostly clear, warm and enjoyable. In the sub-tropical plains, temperature ranges between a maximum of 37 and a minimum of 8 degree Celsius, 28 and 3 degree Celsius in the valleys and 16 to 6 Celsius in the mountains.
Actually, Nepal is beautiful in all seasons. Different seasons offer Nepal differently. However, October/November and March/April are regarded the best months to visit Nepal to ensure good view of the Himalayan ranges with blue sky both for the cultural tours and trekking on the high hills and mountains.