Scattered thundershowers have been forecast over Tamil Nadu, Kerala, coastal and south interior Karnataka.
They could linger at a few places, thereafter, according to an India Meteorological Department (IMD) outlook, on Wednesday.
An extended outlook valid for the next seven days also spoke about the possibility of scattered rainfall over south peninsular India.
A swath of rain is forecast to extend across southern Bay of Bengal all the way from east Bay of Bengal during this period.
Satellite imagery on Tuesday afternoon showed rain-bearing clouds over parts of coastal Tamil Nadu, North and South Bay of Bengal and South Andaman Sea.
The IMD also traced a causative cyclonic circulation over the Gulf of Mannar off the south Tamil Nadu coast.
Another cyclonic circulation from erstwhile cyclone ‘Nilam’ hung over north coastal Andhra Pradesh, from which a trough of low pressure lay extended until Assam and Meghalaya.
In view of these features, the IMD has forecast thundershowers at many places over Nagaland, Manipur, Mizoram, Tripura and Andaman and Nicobar Islands.
Rain or thundershowers would break out also at many places over north coastal Andhra Pradesh, coastal Odisha and Gangetic West Bengal.
Meanwhile, night temperatures continued to be below normal over north and adjoining Central India during the 24 hours ending Tuesday morning.
They fell by 4-6 deg Celsius over isolated pockets of interior Maharashtra, east Uttar Pradesh and Assam and by only slightly lesser margin over Madhya Pradesh, Gujarat, Maharashtra, Jammu and Kashmir, Haryana and Uttar Pradesh.
The lowest minimum of 10 deg Celsius was recorded at Malegaon in Maharashtra.
The night temperatures may lift in view of the expected arrival of a warm western disturbance over the Himalayan region by Friday.
In this manner, it might also trigger rain and snow in the higher reaches and foggy mornings for the plains of the region.