In India, only during a specific time of the year it rains. The season as well as the phenomenon that causes rain is known as monsoon. They are basically of two types, the Southwest and the Northeast. The two names are given after the directions of the winds coming from. The Southwest monsoon is the major one, as it is the cause of rain in most parts of the country, and is one of the most important factors that decide how the crops (and therefore the economy) will do. It lasts from June to September. It hits the west coast the most, as crossing the western ghats and reaching the rest of India is difficult for the winds. Therefore the western coastline is much greener than the interior. The Northeast monsoon hits the east coast between October and February, mostly in the form of occasional cyclones which leads to a lot of decimation every year. Northeastern India is the only region that gets rains from both the monsoons, which consequently results in the highest rainfall in the world.
At least three seasons in a year, are experienced by India, Summer, Rainy Season (or "Monsoon") and Winter, though in the tropical South calling the 25°C (77°F) weather "Winter" would be stretching the concept. The Northern region experiences comparatively more hot Summers and cold Winters, but except in the Himalayan regions, snow is almost unheard of. November to January is the winter season and April and May are the hot months when rains are desperately awaited. There is also a brief spring in February and March, especially in North India.
There are various opinions on whether any part of India actually experiences an Autumn, but the ancients mentioned the Autumn season among the classification of the six seasons (or ritus - Vasanta - Spring, Greeshma - Summer, Varsha - Rainy, Sharat - Autumn, Shishira - Winter, Hemanta - "Mild Winter")in a year.
The India Meteorological Department (IMD) declares four official seasons:
- Winter starts from December and ends in early April. December and January are usually the coldest months of the year, when temperatures average around 10–15 °C (50–59 °F) in the northwest; proceeding towards the equator the temperatures rise, at the highest of around 20–25 °C (68–77 °F) in mainland India's southeast.
- Summer occurs from April to June (April to July in northwestern India). For the western and southern regions, the hottest month is the April whereas for northern regions, May is the hottest month. The average temperature is around 32–40 °C (90–104 °F) in most of the interior.
- Monsoon also known as rainy season, starts from June and continues until September. The season is mainly commanded by the humid southwest summer monsoon, which gradually sweeps across the country starting in late May or early June. Monsoon rains begin to diminish from North India at the beginning of October. South India typically receives more precipitation.
- Post-monsoon season lasts from October to December. In northwestern India, October and November are generally cloudless. Each year Tamil Nadu receives most of its precipitation, in the northeast monsoon season.
The Himalayan states, being more temperate, experience an additional two seasons: autumn and spring. Traditionally, Indians speak about six seasons, each lasting for two months. These are the spring (Sanskrit: vasanta), summer (grīṣma), monsoon season (varṣā), early autumn (śarada), late autumn (hemanta), and winter (śiśira). These are based on the astronomical division of the twelve months of a year into six parts. The ancient Hindu calendar also states the six seasons in its arrangement of months.