The Bay of Bengal branch of south-west monsoon moves towards northeast carrying more moisture and they give heavy rainfall in this region. As they move further towards west, they carry less moisture content with themselves resulting in decrease in rainfall in the west

Seasonal reversal of wind direction over the Indian subcontinent takes place due to pressure differential. El Nino has major role to play in the seasonal reversal of wind direction over the Indian subcontinent.

The monsoon begins from the first week of June and advances quite rapidly to cover almost the whole country by mid-July. Hence, the bulk of rainfall in India concentrated over the months of a few months; mainly June to August.

The Tami Nadu coast receives winter rainfall because of movement of low-pressure conditions to the Bay of Bengal.

The Bay of Bengal is the centre of various pressure changes and hence there is always a chance of development of cyclone. Due to this, the delta region of the eastern coast is frequently struck by cyclones.

The parts fall in the rain shadow area of the Aravalli. Hence, they are drought prone as they don't receive much of rainfall.

There is regional variation in the climatic conditions of India. Temperature and Precipitation vary from place to place and season to season.
→ In summers the temperature rises up to 50°C in parts of Rajasthan, whereas it may be around 20°C in Pahalgam in Kashmir.
→ In winters night temperature in Drass in Kashmir may be minus 45°C, whereas in Tiruvanantapuram in Kerala may have a temperature of 20°C.
→ In Andaman Islands the difference between day and night temperature may be hardly 7° - 8°C.
→ Coastal areas experience less contrast in the temperature, whereas seasonal contrasts are more in the interior of the country.
→ There is decrease in rainfall generally from east to west in the northern plains.
→ Most part of India recieve rainfall from June – September, whereas some parts like the Tamil Nadu coast gets a large portion of its rain during October and November.

Following are the factors responsible for the mechanism of monsoon:
→ The differential heating and cooling of land and water creates low pressure on the landmass of India while the seas around experience comparatively high pressure.
→The Inter Tropical Convergence Zone (ITCZ) is normally positioned about 5°N of the equator. It shifts over the Ganga plains during summer. It is also known as the monsoon trough during the monsoon season.
→ The high pressure area, east of Madagascar is approximately 20°S over the Indian Ocean. This area affects the Indian Monsoon.
→ The Tibetan plateau gets intensely heated during summer. This results in strong vertical air currents and formation of high pressure over the plateau. This high pressure zone is about 9 km above the sea level.
→ The westerly jet stream move to the north of the Himalayas, and the tropical easterly jet stream moves over the Indian Peninsula during summer.
→ The periodic change in pressure conditions between Pacific Ocean and the Indian Ocean that is known as the Southern Oscillation or SO also affects the monsoon.
→ The difference in pressure over Tahiti and Darwin is computed to predict the intensity of the monsoons. Tahiti (18°S/149°W) lies in the Pacific Ocean and Darwin (12°30'S/131°E) lies in northern Australia. If the pressure differences are negative, it means a below average and late monsoon.