Proper noun

1. A sustained sea-surface temperature anomaly of magnitude greater than 0.5°C across the central tropical Pacific Ocean, associated with a negative anomaly and producing predictable variations in local and regional weather patterns.

   Climate scientists think a La Niña event may develop this summer, meaning water temperatures in the Pacific Ocean will be cooler that normal. Although the relationship is not fully understood, historically there tends to be more hurricane activity during a La Niña event. — Houston Chronicle, 5/23/2007