In this file photo monsoon storm clouds move over the royal palace in AgartalaARINDAM DEY/AFP/Getty Images

Crop-nourishing monsoon rains hit Kerala coast in India's southwest on Tuesday, a source from the weather office said. The rains have come three days ahead of schedule. 

The monsoon, the lifeblood of the country's $2 trillion economy, delivers nearly 70 percent of rains that India needs to water farms and recharge reservoirs and aquifers. Nearly half of India's farmland, without any irrigation cover, depends on annual June-September rains to grow a number of crops.

The southwest monsoon has been advancing well and will cover some parts of Kerala on Tuesday, in line with the forecast of the India Meteorological Department, a senior weather department official, who did not wish to be named as he was not authorised to talk to media, said.

The India Meteorological Department declares the arrival of monsoon rains only after parameters measuring the consistency of the rainfall over a defined geography, intensity, cloudiness and wind speed are satisfied.

Skymet, the country's only private weather forecaster, said monsoon hit Kerala coast on Monday.

Rains usually lash Kerala state on the south coast around June 1 and cover the whole country by mid-July. Timely rains trigger planting of crops such as rice, soybeans and cotton.

India is likely to receive average monsoon rains in 2018, the weather office said last month, raising the possibility of higher farm and economic growth in Asia's third-biggest economy.

[Source- Reuters] Note: This article has been updated to add that monsoon has hit Kerala on Tuesday, May 29.