The Australian Bureau of Meteorology (BOM) this week said the conditions could emerge as early as July, maintaining its outlook of the chance of the event at 70 percent.
El Nino, a warming of sea-surface temperatures in the Pacific, can trigger both floods and drought in different parts of the globe.
The worst El Nino on record in 1997/98 was blamed for massive flooding along China's Yangtze river that killed more than 1,500 people.
Below are some key commodities that could be affected by its return.
GRAINS, OILSEEDS, LIVESTOCK
El Nino could bring dry weather to Australia, which is already struggling with a drought. El Nino could also curb wheat, sugar and cotton production in the country.
An El Nino episode usually results in below-average rainfall in main palm oil producers Indonesia and Malaysia, cutting yields and pushing up global prices.
It could also hurt crops in Thailand, one of the world's largest rice exporters, potentially worsening drought conditions.
El Nino would bring milder-than-normal temperatures to the major crop production areas of the U.S. Midwest. Iowa and Minnesota would benefit from the event's tendency for wetter-than-normal summers as the western Corn Belt continues to recover from a drought.
But excessive rains in the saturated soils of the eastern Corn Belt could be troublesome, particularly following this year's overly snowy winter. Drought-hit California, a major dairy and wine grape state, could see more rain than normal.
In China, El Nino could bring more rain to areas south of the Yellow River and cause flooding in the country's major rice and cotton growing regions.
Lower-than-normal temperatures could also occur in the country's top corn and soy areas in the northeast, leading to frost damage and lower grain output.
A strong El Nino in India would trigger lower production of summer crops such as rice, sugarcane and oilseeds. India is the world's No.2 producer of rice and wheat.
Previous El Nino episodes caused severe dry spells in the Philippines, affecting vast tracts of farmland. A rice shortfall due to typhoons and drought connected to El Nino in 2010 prompted record imports of the national staple.
A returning El Nino could cut output in main producers Ivory Coast, Ghana and Indonesia. Expectations that the global market will experience a second straight deficit in 2014 sent prices to more than two year highs earlier this year.
Erratic weather could affect the development of coffee cherries and cocoa pods. In Indonesia, the world's third-largest cocoa producer, El Nino usually means extremely dry weather.
Indonesia competes in the robusta coffee market with Vietnam, which would also suffer from an El Nino.
El Nino usually brings warmer winters to Brazil, the world's top coffee producer, reducing the risk of coffee frost. But heavy rains would crimp production.
Drier weather could also help beat back moisture-loving roya or leaf rust fungus that is ravaging coffee plantations in Central America.
In 2009, El Nino turned Indian monsoon patchy, leading to the worst drought in nearly four decades which helped push global sugar prices to their highest in around 30 years.