By Ratnajyoti Dutta

NEW DELHI (Reuters) - India's monsoon season is set to enter its withdrawal phase by this weekend after a late surge in rainfall delayed the retreat by a fortnight, a senior weather official said, boosting output prospects for summer crops.

Usually, the monsoon season enters its retreating phase from early September, and withdraws completely from the grain bowl belt of northwest India by the middle of the month.

"We expect the withdrawal of monsoon rains to start from Rajasthan and adjoining north-west India in the next three-to-four days," said the official, who did not wish to be named as he is not authorized to speak to the media.

The annual monsoon rains are vital because over half of India's farmlands lack irrigation, and the farm sector accounts for 14 percent of the national economy.

The monsoon is the main determinant of rural spending on consumer goods ranging from lipstick to cars as two-thirds of its 1.2 billion people live in villages. Its failure pushes up food prices.

In the first month of the season this year, the monsoon season registered the weakest rainfall this century, raising the prospect of the first widespread drought in five years after 2009 when the rains were 22 percent below average.

But the monsoon narrowed the shortfall during the key sowing month of July and revived in the second half, helping farmers plant crops late this summer season with the spread of monsoon.

Monsoon rainfall has been 11 percent below average since the start of the four-month season in June.

The late surge in the rains has led to flash floods in many states including Kashmir where hundreds of people were killed and tens of thousands were made homeless.

Experts ruled out a record harvest for the second straight year in the 2014/15 crop year that began from July, but hoped there would be comfortable harvest from the summer season.

"The late monsoon surge boosted prospects of winter sowing," said farm minister Radha Mohan Singh, speaking at an event to review the country's preparedness for the winter sowing season.

Singh's ministry is expected to release its first estimates for summer crops such as rice, corn, sugarcane, soybean and cotton on Friday, discounting damage due to drought and floods during this year's monsoon season.

Experts held the late surge and the delayed retreat of the monsoon would aid the growth process of the crops, minimizing the impact of this year's late sowing due to the poor start of the four-month long rain season.


(Editing by Clara Ferreira Marques)