The upper air cyclonic circulation over Comerin (Kanyakumari) area and its neighbourhood resulted in the rains, the Regional Meteorological Centre here said.
It forecast rain or thundershower in different parts of the state for the next 24 hours.
The showers brought down the temperature, which had been soaring with the peak three-week long summer season setting in last week.
Tiruchirappalli, Coimbatore, Tirunelveli, Virudhunagar and Nilgiris were among the districts which received good rains, the MeT office said.
Chennaites reeling under hot and humid climate for the past few days woke up to a pleasant morning with the light showers, bringing them respite.