The U.N. weather agency says La Nina conditions re-emerged in August and will likely continue through the rest of 2011 and into early next year.

The La Nina phenomenon is characterized by cooler sea surface temperatures in the central and eastern tropical Pacific, greater rainfall in the southern Pacific, and dry conditions in parts of east Africa, southwest Asia and the southern United States.

The World Meteorological Organization says La Nina conditions could strengthen to "moderate intensity" but probably will be considerably weaker than the most recent ones linked to flooding and drought in parts of the world.

La Ninas -- the opposite of El Ninos -- normally trigger some extremes, such as flooding in Australia and drought in Texas.