* Met office still hopeful of an average monsoon
* Poor monsoon could dent hopes for economic rebound
* A cyclone on east coast to fizzle out this week
* Drought hit states not sure of timely monsoon (Adds quotes, graphics, details)
By Ratnajyoti Dutta
NEW DELHI, May 15 (Reuters) - India's monsoon rains may arrive on the southern coast around June 3, the weather office forecast on Wednesday, a late debut that will raise fears any revival for drought-hit tracts of southern and western farmland could be delayed.
The rains, which run from June to September, are vital for the 55 percent of farmland without irrigation in India, one of the world's largest producers and consumers of food.
"The date of onset of southwest monsoon over Kerala is likely to be on 3rd June," the India Meteorological Department said in a statement, adding the forecast has an error margin of four days, a time frame treated as normal.
Last year, the monsoon hit Kerala four days after the June 1 date forecast by the weather office, and the season brought below average rainfall across the country, leaving several key sugar and cotton-growing states parched by drought.
A poor monsoon could be bad news for the coalition government as it gears up for a series of state elections this year and a national election due by May 2014 as deficient rainfall could dent hopes for a fast economic rebound and reignite inflation.
The weather department said it was too early to say how the monsoon would behave over these states, echoing caution from Food Minister K.V. Thomas last month.
"Let the monsoon first arrive and then travel at least for about two weeks, then only would it be possible to forecast how the monsoon would be over the drought hit states," D.S. Pai, the lead forecaster at the Indian weather office, told Reuters from the western city of Pune.
He added that the slight delay forecast for the onset took into account a cyclone currently on the east coast which should fizzle out this week and that would help the monsoon regain momentum.
"There is no need to raise any alarm bell at this juncture as the monsoon could even hit the Kerala coast one day ahead of its normal date as per model assessment," he said.
Weather office data shows that the monsoon hit the Kerala coast as late as June 10 in 2005, over-running the onset forecast by three days, but the four-month rainy season still had overall average rainfall.
"The delay of 3 days is manageable and we won't see any impact on crops, productivity and others... If there is any further delay, it will be a cause of concern," said Harish Galipelli, head of commodities, at JRG Wealth Management.
India's weather office has forecast an average monsoon in 2013 for the country overall.
Timely arrival of the rains are necessary to boost prospects for farm output, by giving crops planted by farmers sufficient time to mature and yield a bumper harvest.
The rainy season starts over the Kerala coast and unfurls over the rest of India and neighbouring Bangladesh, Bhutan and Nepal by mid-July.
The meteorological department will update its overall forecast for the monsoon in June, when the rains are expected to have spread over half of India. (Additional reporting by Siddesh Mayenkar in MUMBAI; editing by Jo Winterbottom and James Jukwey)