La Niña is over. Scientists now say it was stronger than it seemed.

One of the most accurate long-range forecast models shows the equatorial Pacific warming up during summer and autumn. But not all models agree. The key monitoring region, called Niño 3.4, is outlined. (Ben Noll/The Washington Post/Data source: ECMWF/Copernicus Climate Change Service) By Scott Dance and Ben Noll

La Niña is over, scientists declared Thursday. And while the climate pattern was notably brief and had been waning, scientists said the episode was not as weak as it once seemed.

When the planet-cooling climate pattern emerged this year, scientists said it developed later and in a weaker state than they had expected. But researchers say that is because unusual warmth that has dominated the Pacific and other global oceans for the past two years masked La Niña, which is define