During the initial days of the June-September wet season, summer crops such as rice, corn, soybean and cotton are not greatly affected by the quantity of rains. The distribution of rainfall in mid-July, after the monsoon covers the entire Indian landmass, is more important for their growth.
India's farm sector accounts for 14 percent of its nearly $2 trillion economy. Poor rains this year could hit the summer crops, raising food prices and pressuring economic growth that has nearly halved to below 5 percent in the past two years.
"We expect the weak phase to continue until the middle of next week," said a weather official who did not want to be named. Monsoons this year started on a weak note, arriving over India's southern coast about five days behind the usual date of June 1.
India's weather office forecast below average rainfall in 2014, with a one in three chance of drought as a weather pattern often associated with drought in South Asia could emerge in the second half of the season.
El Nino, a weather phenomenon marked by warming of the temperature of the sea surface in the Pacific Ocean, could cause droughts in the Asia Pacific, including India.
"There could be a weak to moderate El Nino during the last week of July to early August, through it is still in a neutral condition," said L.S. Rathore, the head of the India Meteorological Department (IMD).
IMD estimates that there is a 33 percent chance that the monsoon will be "deficient," defined as delivering rainfall of less than 90 percent of the long-period average (LPA).
The weather office defines average, or normal, rainfall as between 96 percent and 104 percent of a 50-year average of 89 cm for the entire season.
Half of India's farmland lacks access to irrigation, making many farmers particularly dependent on monsoon rains. The nation plans to expand irrigation coverage by at least a tenth by 2017 to cut its dependence on the seasonal rains.
Rains in the coming two to three days are likely to be concentrated in India's western coastal regions where farmers favour cultivation of coffee and rubber, the weather official said.