India is at its most pleasant between October & march when much of the country enjoys balmy blue skies & fresh clean air. In the north from December to late February the nights turn chilly & a sweater or jacket is required. By mid-march the days start getting warmer & from late April the temperature in central India becomes too hot for comfortable travel. 

In May the dust & thunderstorms with occasional showers precede the monsoon. This is when the British Raj used to move to the hills, as many Indians still do. Most of India, with the exception of the Trans-Himalayan area of Ladakh, is in some way affected by the southwest monsoon. In Kerala the rains arrive by the first week of June. They then make their way northwards, reaching Mumbai in the middle of the month & Delhi by early July. The rains last for almost three months & after the initial chaos of flooded roads, the people take the downpours & regular drenching in their stride. By the end of September the humidity decreases & in October temperatures begin to drop. In Kashmir, Himachal Pradesh & Uttar Pradesh, the winter months are often extremely cold. These areas are best visited from April to July or after the monsoon. Sikkim & Arunachal Pradesh, while part of the Himalayan chain, are most affected by monsoons & have rain from May. Southern India has more regular climate that is also controlled by the monsoon. The southeast coast gets rain from October to late December as the northeast monsoon moves across the Bay of Bengal.