1. Temperature: With increase in the Monsoon rainfall, the temperature falls and it starts rising in September. In Rajasthan it touches, 38°C in the month of September.
2. Atmosphere Pressure: Low pressure areas are densely centralised over the Thar Desert of Rajasthan and Punjab and high pressure area develops over the Indian Ocean in South.
3. Direction of Winds: The winds move from the South-West ocean towards the North East-Plains and are called the South-West or the Monsoon winds.
4. Rainfall: The Indian Peninsula divides the South-West monsoon into two branches, i. e. (a) the Arabian Sea and (b) the Bay of Bengal branch.
(a) The Arabian Sea: is stronger than the Bay of Bengal. It strikes the Western Ghat and sheds about 250 to 300 cm of rainfall. Its velocity here is reduced to the minimum. Therefore, the inner plateau receives very low rainfall from Arabian Sea. Its Nagpur branch moving between the Narmada- Tapti Valley, merges with the Bay of Bengal. Another sub-branch reaches directly the Western Himalayas, moving through Rajasthan which receives very little rainfall because of its location parallel to the Aravalli range.
(b) The Bay of Bengal: is a sub-branch which moves towards Arunachal Pradesh and Assam. After striking the Garo hills this sub-branch brings heavy rainfall in this area. Mawsynram of Cherapunji receives maximum rainfall from it. Another sub-branch moves ahead along with Tarai of Himalayas. Bihar, Uttar Pradesh, Chhattisgarh, Jharkhand and Uttarakhand receive rainfall from it. The amount of rainfall decreases as it moves towards West. The Western Punjab and Rajasthan receive very little rainfall from it.
