La Nina is defined as abnormally high sea temperatures in the western Pacific ocean.
Often following an El Niño event, the waters of the western Pacific become a lot warmer than usual, and the upwelling of cold waters along the west coast of South America becomes more pronounced than usual. This event, the opposite of El Niño, is known as La Niña.
La Niña events effect climatic conditions around the globe and are, generally speaking the opposite of El Niño, including:
Drier and warmer conditions in the southern states of the USA, often leading to “Wild Fires”;
Colder winters in the northern USA and Canada as the polar jet stream moves further south than usual;
Increased hurricane activity in the western Atlantic;
Wetter than normal conditions in northern Australia and Southeast Asia and increased monsoon rains over India.