Thiruvanathapuram, Jun 8 (PTI) After a delay of almost seven days, Southwest Monsoon today finally hit Kerala, marking the official commencement of rainy season in the country, as heavy showers in the southern state left one person dead.

"Southwest monsoon has set in over Kerala and Lakshadweep," said K Santosh, head of India Meteorological Department's (IMD) Thiruvananthapuram regional centre.

It has also advanced into most parts of Tamil Nadu, some parts of south interior Karnataka and remaining parts of south Bay of Bengal, according to IMD

Several parts of Kerala have been receiving heavy rains since last night which left a 36-year-old man dead due to landslip in Idukki district of Kerala.

Jobi John, former SFI Idukki district president, died and his mother was seriously injured when mounds of earth and rocks fell on their home following heavy rains at Vazhavara early today, police said.

To declare the onset of monsoon over Kerala, the IMD has three important parameters.

The 14 stations at which the rainfall is being monitored for declaring the Monsoon onset over Kerala have reported widespread rainfall for the last 48 hours with more than 60 per cent of stations recording rainfall on June 7 and 8

The Westerly/ West-southwesterly winds of the order of 30-40 kmph were observed upto 600 hPa (approximately upto 4.5 km) over the south Arabian Sea.

The satellite (INSAT-3D) derived Outgoing Longwave Radiation value was less than 200 W/m2 on June 8.

"All these three conditions got fulfilled for the first time today i.e. June 8 since the monitoring was started by IMD from May 10. As a result, the Southwest Monsoon has set in over Kerala, today, the 8 th June 2016.

"The Southwest Monsoon has further advanced into remaining parts of south Arabian Sea, Maldives Comorin area, most parts of Kerala and Tamil Nadu, some parts of south interior Karnataka, remaining parts of south Bay of Bengal and some more parts of central Bay of Bengal," the IMD said.

The IMD in its initial forecast had said that monsoon will hit Kerala on June 7. It had yesterday said that onset of monsoon will be by June 9.

The usual date for onset of monsoon is June 1.

The season is also expected to witness "above normal" rainfall after two consecutive seasons of weak monsoon.

In 2015, the monsoon deficiency was 14 per cent with Northwest India recording a deficiency of 17 per cent, followed by 16 per cent in Central India, 15 per cent in Southern Peninsula and 8 per cent in East and North-east India.

In 2014, the monsoon deficiency was 12.3 per cent of the LPA.

Agriculture, which contributes 15 per cent to India's GDP and employs about 60 per cent of the country's population, is heavily dependent on monsoon as only 40 per cent of the cultivable area is under irrigation.

Due to poor monsoon in 2015-16 crop year (July-June), 10 states have declared drought.