Global Effects

Global Impacts.
Present, Predicted and Past effects of La Niñas.
Plus links to additional information.

Present Effects of La Niña

As a rule, the effects of La Niña are more direct and dramatic during the Northern Hemisphere winter. La Niñas may affect weather patterns in certain parts of the world, causing abnormally high rainfall in southeast Asia and dry conditions in the desert areas of South America. Some impacts of previous La Niñas include:

Abnormally heavy monsoons on the Indian subcontinent.
In the United States, colder and snowier winter in the northern states west of the Great Lakes. Drier than normal winter in the Southeast. Warmer and drier winters in the Southwest. Enhanced hurricane activity around the mid-Atlantic states.
Torrential rains leading to floods in Southeast Asia.
Wet weather in eastern Australia.
Cool and wet winter in southeastern Africa.

Global Impact Map

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Hurricanes

Images/Movies of Hurricanes
Hurricane Outlook

There is an increased likelihood of above-average tropical storm and hurricane activity over the North Atlantic during August-October 1998 in response to developing La Niña conditions, according to a consensus reached by scientists at the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center (CPC), National Hurricane Center (NHC) and Hurricane Research Division (HRD). There is also an increased likelihood of more hurricanes reaching major hurricane status during this period.

In the past, La Nina episodes have contributed to active hurricane years by reducing the variation in winds with height (termed vertical wind shear) over the tropical North Atlantic and the Caribbean Sea. This reduced vertical wind shear is expected to develop over the next several months in response to the ongoing La Nina conditions. Also in the tropical North Atlantic, if the present abnormally warm sea- surface temperatures persist, then they will also contribute to enhanced activity during this period.

Predicted Effects of La Niña

See the forecast section.

Past Effects of La Niña

The National Weather Service Climate Analysis Center site shows effects on U.S. temperatures and precipitation of strong La Niñas in the past during different times of the year.

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