What impact could El Niño have on agricultural commodities?

It is looking increasingly likely that an El Niño weather phenomenon will develop in the Pacific Ocean later this year. This has raised fears that crop production across the Americas, South-East Asia, India and Australia could be disrupted. However, with the potential exception of some tropical agricultural commodities, such as sugar and coffee, the impact on prices of an El Niño should be small and, in some cases, harvests could actually benefit.