For the city of Chennai and the state of Tamil Nadu, Southwest Monsoon is not the main rainy season. However, despite that, there have been satisfactory rains for Chennai.
In fact, while the Nungambakkam observatory saw 23 mm of rains in the last 24 hours, it has recorded 126.3 mm of rainfall so far against the usual average of 146.2 mm for the month of September.
Chennai is expected to continue seeing showers but they will not be heavy but light to moderate rains will be seen. In fact, within this week, Chennai will easily be able to reach the 142 mm mark.
There is a Cyclonic Circulation over Bay of Bengal which will become a Low Pressure Area soon. A trough is also extending from this system along the East Coast up to Tamil Nadu. There is also convergence and turning of winds. The system is a slow-moving one and will persist for some time. Thus, we can expect good rains for Chennai for the next few days.