The opposite of El Niño, La Niña is a weather phenomenon caused by abnormally cold waters off the coast of Chile. For unknown reasons, a warm pool of water between Chile and Australia moves west during La Nina episodes, allowing more cold water to upwell off the coast of Chile. La Nina's effects are basically the opposite of her brother. During these events, we expect colder than normal conditions across most of the US. Drought is also possible in the southeast US and along the west coast of the US, as well as in dry areas of South America. The monsoons in India are heavier than normal.

For the last 3 years or so (1999-2001) we have been experiencing La Niña-type conditions. This has been evident from my home in California. The last few years have been rather dry, and quite cold. We have seen snow down to the floor of the Sacramento Valley at least twice during this event, which is quite rare. Snow has dusted the coast range several times. However, it has been drier than normal. As of Februrary 2001, the climate is showing signs of returning to El Niño conditions. California has become wet again, and the waters off Peru and Chile have started warming. We can expect the next year or two to be similar climatically to 1997-1998, the time of the last El Niño