Japan's weather bureau said an El Nino weather pattern was strengthening and that the phenomenon could grow this year to match or exceed levels last seen six years ago.
In 2009, the El Nino - or a warming of sea-surface temperatures in the Pacific - brought the worst drought in four decades to India. It razed wheat fields in Australia and damaged crops across Asia. Food prices surged.
Currently, the conditions of the atmosphere and the ocean suggest a characteristic feature of El Nino more clearly than a month ago, Japan's weather bureau said on Wednesday.
"The sea temperature was 1.2 degree Celsius higher than a base temperature in May, up from 0.8 degrees the previous month, meaning that El Nino is growing," Ichiro Ishikawa, forecaster at Japan's weather bureau told Reuters on Wednesday.
"In case of the 2009 El Nino, sea temperature hit 1.4 degrees above a base temperature at its peak in December 2009. So the current one is expected to grow to a similar degree or larger than the 2009 El Nino," he said.
Japan Meteorological Agency, which previously said it expects the El Nino to continue into autumn, now sees a possibility of it continuing into winter.
A strong El Nino will roil economies that are heavily dependent on agriculture, particularly India which is already reeling from bad weather. It would also unhinge supply chains of commodities such as rice, corn and palm oil.
Australia's Bureau of Meteorology said on Tuesday that Pacific Ocean temperatures continue to warm, supporting El Nino weather conditions for the rest of 2015.