An El Niño is forecast for the winter ahead, and we all know what that means. Or do we? El Niño—that cyclical warming of the equatorial Pacific Ocean—has long been associated with wet winters across much of the West. Which is always welcome news across the chronically water-short region. But in reality, whether El Niño actually delivers greater-than-normal precipitation is strictly a toss-up, says Jan Null, owner of Golden Gate Weather Services, a consultancy based in Saratoga, California.