The retreating monsoons occur during the months of

The retreating monsoon season, also known as the post-monsoon or North-East monsoon season, occurs during the months of October and November [2]. By the end of September, the southwest monsoon winds weaken as the low-pressure trough over the northern plains moves southward in response to the sun's apparent movement [2]. This transition period is marked by clear skies and a rise in temperature, often referred to as 'October heat' [2][t2]. While the retreat begins in northwest India around mid-September, the core months for the retreating monsoon across the subcontinent are October and November [1][c5]. By early November, the low-pressure system shifts over the Bay of Bengal, leading to rainfall along the southeastern coast of India, particularly Tamil Nadu [1][t2]. Official classifications by the IMD and standard textbooks categorize October to mid-December as the retreating monsoon period [c5][t8].

Sources

1. [1] INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.) > Chapter 4: Climate > Season of Retreating Monsoon > p. 37
2. [2] CONTEMPORARY INDIA-I ,Geography, Class IX . NCERT(Revised ed 2025) > Chapter 4: Climate > Retreating/Post Monsoons (The Transition Season) > p. 32