New Delhi, June 18 -- How badly will El Niño impact weather patterns this year? Some forecasters fear that it may turn out to be the worst on record. This cyclical phenomenon is a menace for the Indian monsoon.

As winds blowing from east to west over the equatorial Pacific Ocean periodically weaken, warm surface water blown to the Asian side slops towards the American landmass.

This reduces rainfall in large parts of Asia all the way to the tropics and beyond, India included, though it also results in extra rain elsewhere.

El Niño's strength is measured by surface water temperature, with a rise greater than 2deg Celsius above the long-term average recorded by the US classified as strong.

This year, the mercury could go past ...