On Thursday, federal forecasters issued an "El Niño watch," indicating a 50 percent chance El Niño will develop this summer or fall.
However, El Niño's return isn't guaranteed.
"While all models predict warming in the tropical Pacific, there is considerable uncertainty as to whether El Niño will develop during the summer or fall," The National Oceanic Atmospheric and Administration said in their announcement. "If westerly winds continue to emerge in the western equatorial Pacific, the development of El Niño would become more likely."
According to the Associated Press, Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research, agreed that an El Niño is brewing on the horizon.
"This could be a substantial event and I think we're due," Trenberth said. "And I think it could have major consequences."
El Niño's wet weather would be welcome in places like California, deep in the midst of drought.
"If they get too much rain, I think they'd rather have that situation rather than another year of drought," Halpert said. "Sometimes you have to pick your poison."
The last big El Niño event was 1997-1998, which ended up causing $3 billion in agricultural damage. Read more here.
Iowa-based KCCI News 8 looked at what to expect with El Niño. In addition to rain for drought-stricken California and southern states, it could lead to fewer Atlantic hurricanes and a mild winter next year for the nation's northern tier.
Elsewhere in the world, the return of El Niño could mean an even hotter year, with billions of dollars is losses for food crops.