Current weather conditions indicate that monsoon is unlikely to start receding before early October, more than a month later than usual, the head of the weather office said on Friday.

Annual monsoon rains are crucial for farm-dependent economy. The monsoon generally begins in June and starts to retreat by September 1, but rains have continued beyond that date this year and triggered fatal floods in Maharashtra, killing hundreds of people.

"The withdrawal of the monsoon, which is already delayed, is ruled out for at least the next 10 days as weather conditions have not become favourable for the season to end," Mrutyunjay Mohapatra, director general of the state-run India Meteorological Department (IMD), told Reuters.

The country relies heavily on the monsoon for irrigation, though crop damage and delayed harvests can result if the rainfall persists.

This month's rainfall has intensified over central, southern and western India, causing floods that have swamped cane and rice fields.

"We can see that monsoon rains have improved steadily after a weak, delayed start in June and we now believe that overall rainfall this season will be either normal or above normal," Mr Mohapatra said.

Two senior weather department officials told Reuters this month that monsoon rains were likely to be above average for the first time in six years.

The IMD defines average, or normal, rainfall as between 96 per cent and 104 per cent of a 50-year average of 89 cm for the entire four-month season.

Monsoon rains, which deliver about 70 per cent of the country's annual rainfall, arrived on the western Kerala coast on June 8, nearly a week later than usual.

The driest June in five years and a below-average July stoked fears of a drought, but rains picked up in August and September as both the El Nino weather pattern and the Indian Ocean Dipole (IOD) phenomenon turned favourable.

A strong El Nino, marked by a warming of the surface of the Pacific Ocean, can cause severe drought in Australia, Southeast Asia and India, while drenching other parts of the world, such as the US Midwest and Brazil.

The IOD is characterised by higher sea-surface temperatures in the Indian Ocean and south-westerly winds that bring rain to the Indian sub-continent.