Earlier this fall, it looked like an El Niño was setting up, Douglas said, but the chances of that happening have now dropped to 53 percent. El Niño's, when they happen, tend to push the jet stream southward, upping the chances of wet weather in the south-central and southeastern U.S. and mild, dry conditions in the northern states.
But those trends are far from a sure thing. Last year's La Niña, for example, led many meteorologists to call for a cold and snowy winter up north. Instead, much of the country saw record-breaking warmth.
To fine-tune his predictions each fall, meteorologist Larry Cosgrove considers the ENSO alongside other weather-influencing conditions, including sunspot number, wind speeds in the upper atmosphere and the severity of recent droughts.
He then looks back through decades worth of data to find analogous years for each condition. Finally, he throws these parallel seasons together, using what he calls his own "whirring blender technology" to come up with predictions for the coming months. His method, he says, is accurate about 60 to 70 percent of the time.