NEW DELHI - India will receive heavy monsoon rains at the tail end of the four-month season, the chief of the weather office said on Tuesday, bringing farmers succour after the driest August in more than a century hit some summer crops.

The monsoon, the lifeblood of India's $3 trillion economy, delivers nearly 70% of the rain needed to water its farms and recharge reservoirs and aquifers.

"Monsoon rains picked up pace after the 3rd or the 4th of this month," Mrutyunjay Mohapatra, director-general of the India Meteorological Department, told Reuters in an interview.

"We now expect that the monsoon will be normal or above normal in September."

Most rice areas except some eastern regions would get good rains, he said.

Also crucial for crops such as corn, cotton, soybeans, sugarcane and peanuts, the monsoon is 7% above average in September but 8% below average since the season began on June 1.

With a weak start, monsoon rains were 9% below average in June before rebounding to 13% above average in July. The monsoon was patchy again in August, with the weather office registering 36% below average rains last month.

The weather office defines average, or normal, rainfall as ranging between 96% and 104% of the 50-year average of 87 cm (35 inches) for the season.

Current weather conditions indicate that the monsoon is unlikely to start receding in the next few days, Mohapatra said.

"We can see new circulations and low-pressure areas over many parts of the country, so there are no symptoms of monsoon withdrawal at this stage," he said. "It's going to be delayed."

The monsoon generally begins in June and starts to retreat by Sept. 17.

The El Nino weather pattern led to poor rains in June and August.

But an active phase of the Madden-Julian Oscillation - a moving system of wind, cloud and pressure that circles the equator - helped bring good rains in July and September, Mohapatra said.

"It clearly shows that El Nino is not the only factor that impacts the monsoon. Other regional variations also play big roles," he said.

(Reporting by Mayank Bhardwaj; Editing by Kirsten Donovan)