India's annual monsoon covered the entire country on Sunday, six days earlier than usual, the state-run weather office said, but rain totals are 10% below average so far this season.

The monsoon, the lifeblood of India's $3 trillion economy, delivers much needed water to farms and restocks reservoirs and aquifers. It also brings relief from the worst of the summer heat.

In a typical year, rains usually lash Kerala state, on India's southwest coast, from around June 1 and move northwards to cover the entire country by July 8.

This year, the monsoon arrived on the coast of southern Kerala state on June 8, more than a week later than normal, and its progress was later stalled by severe cyclone Biparjoy.

However, the monsoon made quick progress this week and has now covered the entire country, the India Meteorological Department (IMD) said.

India received 10% below normal rainfall in June, but some states received as much as 60% lower rainfall than the normal.

But India is likely to receive an average amount of rain in July despite the likely emergence of the El Nino weather pattern, the IMD said on Friday.

Bountiful monsoon rains in July would ease concerns about the output of summer crops, promising higher incomes in the countryside where most Indians live. As almost half of the country's farmland lacks irrigation, Indian farmers depend on the monsoon.