By Ratnajyoti Dutta
NEW DELHI (Reuters) - Rainfall in September, the last month of the monsoon season, is expected to be average in absence of the El Nino phenomenon, the state-run weather department's last update said on Sunday.
El Nino, associated with warmer sea surface temperatures in the Pacific Ocean, often causes droughts in Australia and South Asia including India.
"The current El Nino neutral condition is expected to continue until early next year," D.S. Pai, the lead forecaster of the Indian weather office, told Reuters.
Rainfall between 90 percent and 110 percent of a 50-year average of about 17 cm for the last month of the four month monsoon season is considered average, according to the specification of the India Meteorological Department (IMD).
IMD also retained its average forecast for the June-September monsoon season in absence of the El Nino weather pattern.
The monsoon, vital for the 55 percent of farmland that does not have irrigation, has already brought the heaviest rains in nearly two decades in the first half of the season, giving rise to an expectation of bumper harvests.
In April, IMD had forecast an overall normal monsoon in 2013 with a rainfall estimate of 98 percent of the long-term average.
For the entire season, rains between 96 percent and 104 percent of a 50-year average of 89 cm are considered normal.
During June 1 to August 31, the monsoon rains were 10 percent above average. So far, the rains have been evenly distributed over major crop growing regions of the south Asian country which is one of the world's biggest producers and consumers of farm commodities such as rice, sugar and cash crops like cotton.
Ample rains raised prospects for bumper harvests and higher rural incomes in the world's second most populous country, which could improve retail sales and help rural growth.
Most of the summer planted crops, except rice in some pockets of eastern parts, have already entered their growing stage and now need moderate rains to ensure better yields.
The four-month long rainy season usually starts retreating from western Rajasthan state by mid-September.
(Editing by Keiron Henderson)