The climatic conditions in India and Nepal can vary widely depending on the region and the time of the year. As a guideline, the monsoon in both India and Nepal falls between the months of April through to September. The weather during this time is generally hot, humid and wet. Travel in this region is not generally recommended during this period, unless you are planning to visit the Indian Himalaya when these months are ideal. The ideal time to visit India (other than the Indian Himalaya) and the best time to trek in Nepal is during the non-monsoon months starting in late September through to early April.

India provides the world's most pronounced example of a monsoon climate. The wet and dry seasons of the monsoon system, along with the annual temperature fluctuations, produce three general climatic periods over much of the country:

Monsoon - Hot, wet weather from about mid-June to the end of September.

Retreating Monsoon - Cool, dry weather from early October to February.

Summer - Hot, dry weather from about March to mid-June.