The low pressure area over south-west Bay of Bengal and adjoining Sri Lankan coast still persists, according to weather office sources in Chennai.
The sources told UNI Monday that under its influence, rain or thundershowers were likely at many places in Tamil Nadu and Pondicherry during the next 48 hours.
Isolated heavy rainfall was likely in Tamil Nadu and Pondicherry during the same period.
Chennai, which was being battered by incessant rainfall since Sunday, would experience a few spells of rain, heavy at times, due to the low pressure.
During the last 24 hrs ending at 8.30 am Monday morning, Chennai city received 142.4 mm of rainfall while suburban Meenambakkam recorded 134 mm of rainfall in the same period.
Meanwhile, the Tamil Nadu government declared a holiday for schools and colleges in Chennai, Tiruvallur, Kancheepuram and Cuddalore districts.
A report from Kancheepuram said the district authorities have warned fishermen at Mahabalipuram from venturing into the sea as it would be rough.