Though El Niño’s impacts in the state, particularly Southern California, fell short of expectations, worldwide effects from the event were significant, according to scientists at the National Oceanic and Atmospheric Administration. . . . in its declaration, NOAA estimated a 75 percent chance for a La Niña phase, characterized by cooler-than-average sea temperatures, to roll around this fall, though it’s unlikely to cause extreme changes in the Bay Area’s rainfall, forecasters said.