Nepal’s topographical extremities govern the climate conditions of Nepal. It ranges from tropical to arctic. Low-land Terai region with its maximum altitude at 305m, which lies in the tropical southern part of the country, has a hot and humid climate that can rise above 45 Degree Celsius during the summer. Mid-land regions are pleasant almost all the year round, although winter nights are cool. The northern mountain region, at an altitude above 3,300m has an alpine climate with considerably lower temperatures in winter.
 
People say migrating birds do not have to leave Nepal. Nepal’s weather is generally predictable and pleasant.
The year is divided into 4 seasons of Nepal

Winter (December – February)
Spring (March – May)
Summer (June – August)
Autumn (September – November)

The best season to visit for plant lovers is during spring when the flowers are in full bloom and mountain slopes covered with colorful flowers. Autumn is the most popular tourist season to visit with temperatures in the low to mid 20’s with clear blue skies and extraordinary mountain views. It tends to get colder during winter but a short trek can be easily accomplished at this time of year. Summer is the Monsoon season of Nepal. There is heavy rainfall in mid summer but this is the best time of the year to watch the cascading water falls in the high mountain regions. Winter and summer are considered the less tourist seasons of Nepal.