NEW DELHI - Monsoon rains that mark the start of the four-month rainy season are likely to enter India through the southern coast around June 1, in line with typical patterns, a top government official said on Thursday.

"This is an early indication," Madhavan Rajeevan, secretary of the Ministry of Earth Sciences, said in a tweet.

India's weather office will issue its official forecast for this year's monsoon onset on May 15, Rajeevan said.

Nearly half of India's farmland, which has no irrigation cover, depends on annual June-September rains to grow crops such as rice, corn, cane, cotton and soybeans.

India's weather office said last month the country was expected to get average monsoon rains this year, raising expectations of higher farm output, which is central to the country's economy.

Last year, India's monsoon rains, which typically arrive on the southern tip of Kerala state around June 1 and retreat from the desert state of Rajasthan by September, were above average for the second year in a row - the first time that has happened in more than six decades.

Last year's monsoon rains replenished soil moisture and led to higher crop yields.

(Reporting by Mayank Bhardwaj; editing by Barbara Lewis) ((mayank.bhardwaj@thomsonreuters.com; +91-11-4954 8030; Twitter: @MayankBhardwaj9; Reuters Messaging: mayank.bhardwaj.thomsonreuters.com@reuters.net))