COLOMBO/CHENNAI: Schools were closed across Sri Lanka on Friday due to high air pollution levels as a cyclonic storm passed by its coast, raising strong winds and rain, with forecasts that it will make landfall on India's southeastern coast around midnight.

Authorities deployed nearly 400 disaster relief personnel in Tamil Nadu state, and urged people to stock up on essentials and be prepared to move to shelters as cyclone 'Mandous' approached.

The sky turned cloudy with sporadic rain in Sri Lanka's commercial capital Colombo and other cities as the cyclone pulled pollution from neighbouring India, prompting health authorities to advise that children and elderly to remain indoors.

The India Meteorological Department (IMD) said 'Mandous' has weakened from an earlier severe category, but warned that a storm surge of about 0.5 metre above the high tide was likely to inundate low-lying coastal areas of northern Tamil Nadu and neighbouring Puducherry when the cyclone makes landfall.

Heavy to extremely heavy rainfall was expected in those areas and also further north along the shores of Andhra Pradesh state, IMD said, warning that coastal communities were likely to suffer damage to thatched, mud houses and power and communication lines.

As the cyclone moves away from Sri Lanka, the air quality there is likely to improve during Friday and Saturday, the National Building Research Organisation (NBRO) said in a statement.