The El Nino phenomenon of warming sea surface temperatures in the Pacific could strike as early as the Northern Hemisphere summer, the US weather forecaster warned.
The Climate Prediction Center (CPC) said there was about a 50 percent chance of the weather pattern developing during the summer or autumn, according to Reuters.
The CPC switched its status to El Nino watch for the first time since October 2012.
The last time El Nino affected global weather pattern was in the summer of 2009, lowering temperatures in the Northern Hemisphere. A more severe occurrence was in 1998 when billions of dollars in damage to crops, infrastructure and mines in Australia and other parts of Asia were caused.
The outlook will increase uncertainty in global commodity and energy markets, with coffee, cocoa and natural gas prices roiled by an extended period of extreme weather.
The forecast will also be closely watched by the US oil industry as El Nino reduces the chances of storms in the Gulf of Mexico that could topple platforms and rigs during the Atlantic hurricane season that starts on June 1.
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