Share to Facebook Post to Twitter Email La Niña means that water temperatures in the Central Pacific Ocean are lower than average for at least three months in a row. Courtesy graphic. The world is currently experiencing a La Niña cycle, which means that water temperatures in the Central Pacific Ocean are lower than average for at least three months in a row. The threshold to be in La Niña is at least 0.5 degrees Celsius lower than average, or about one degree Fahrenheit. An El Niño period is the opposite, with water temperatures at least 0.5 degrees Celsius higher-than-average. A La Niña period gets categorized as weak, moderate or strong, but can’t be categorized until it’s over and temperature data can be analyzed. The most recent La Niña was 2017-18. Over the last 50 years, time has been more or less evenly split between La Niña, El Niño, or nothing — water temperatures close to average.