The El Niño–Southern Oscillation (ENSO) causes year-to-year changes in climate, with impacts to sea level, precipitation, and storm frequency. Climate models suggest a possible doubling of these extreme events in the 21st century, with El Niño-like conditions projected to occur more frequently. After an El Niño, Hawai'i generally experiences drier conditions from January-March. A La Niña often brings wetter conditions from December-February. An El Niño phase is characterized by decreased trade wind activity, which allows warm waters to flow west to east. The warm water brings associated cloudiness and rainfall. During La Niña phases, this pattern is reversed. A majority of climate model results suggest that large-scale gradients in sea-surface temperatures will weaken, which will also lead to weakening atmospheric circulation and more "El Niño-like" conditions.