3.7. Retreat of Monsoon

Monsoon starts retreating in September (Figure 12). On the first of September it starts retreating from north-western part of India. This day is the last day of rainy season in Jaisalmer and Barmer in Rajasthan. By 15th September, monsoon leaves Punjab, Haryana, Rajasthan and Gujarat. The area under the monsoon influence shrinks slowly and the monsoon retreats from all parts of India except the southern peninsular region. Monsoon winds in most parts of the country are replaced by the north-easterly trade winds. These winds blowing over the Bay of Bengal pick up moisture from there and cause rainfall in Tamil Nadu.