India has dramatically varying climates throughout the year. The weather is mostly hot during the year and it varies from region to region. The weather cools down from November and remains cool till the beginning of March. The hot weather is from the month of March and is till June. Between June and October, occurs the monsoon rains. The best time to travel in India depends on that particular destination and its climate at that time.
North India: The north has a subtropical land climate with high temperatures in summer and cool winters, with only has a short term rainy season. In May and June, the heat is painful. During July and August there are regular showers. In September, the weather is good as the rain clears and the temperatures drop down a little extent. Both North East and North West India get extremely cold in the winter. It is important to plan your dates carefully if you are planning for tours. In the northwest foothills, the rainy season starts from the beginning of July until the end of August, while in the north east, the rains begin in June until the end of October.
South India: The south India has a tropical climate, and although the temperature varies little throughout the year, the heavy monsoonal rains may cause flooding. The climate in South India is tropical. In Kerala, the temperature is about 30ºC all the year round and the best time to visit is between November and May. The monsoon in Kerala starts in June and lasts till September. Tamil Nadu, in the South West, is the hottest area of the country as the temperatures in the months of May and June very hot. The rainy season in Tamil Nadu is short and runs from early October until early December.
East India: Eastern part is one of the hottest parts of the world from May to July and the arrival of the monsoon with some little rain and more cloud makes very light difference to the temperatures, so that July, August, and September are unpleasantly hot and humid. The cool season from November to March is warm, sunny and dry.
West India: The Western Ghats, the Malabar Coast, southern Assam, Lakshadweep and Andaman and Nicobar Islands have the tropical monsoon climate. It experiences moderate to high temperature with seasonal but heavy and abundant rainfall. The months from May to November have the most rainfall and the rain received during this period is sufficient for vegetation throughout the year. The summers are extremely hot and the rainy season is from the month of June to September.