India's monsoon rains were 24% below average in the week ended June 26, the weather office said on Thursday, as the seasonal rainfall was scanty over central and western parts of the country.

The rains are crucial for farm output and economic growth as about 55% of the south Asian nation's arable land is rain-fed, and the farm sector makes up about 15% of a nearly $2.5-trillion economy that is Asia's third-biggest.

The below-average rainfall has delayed sowing of summer-sown crop such as rice, soybean and corn and threatens to curtail crop yields.

Monsoon has delivered 36% lower-than-normal rainfall since the start of the season on June 1, due to a delay in the onset of monsoon rains, according to data compiled by India Meteorological Department.

Monsoon rains arrived in Kerala on June 8. However, Cyclone Vayu developed in the Arabian Sea drew moisture from the monsoon and weakened its progress.

Revival neededMonsoon has delivered lower-than-normal rainfall since the start of the season on June 1, due to a delay in the onset of monsoon, according to data compiled by IMD.

Monsoon revival needed in 2 weeks to save season, says analyst. Monsoon arrived in the southern state of Kerala on June 8. However, cyclone Vayu developed in the Arabian Sea drew moisture from the monsoon and weakened its progress.