National Oceanic and Atmospheric Administration:
"El Niño can have a wide variety of effects including lowering or raising temperatures, increasing or decreasing precipitation, extending or reducing drought conditions, enhancing or lowering risk for tropical cyclones, and increasing the potential for coral bleaching.
The evolution, strength, and impacts of individual El Niño events vary, in some cases greatly, throughout their duration. This makes constant monitoring and awareness extremely important for decision makers across multiple sectors."
El Niño Impacts and and Outlook: Western Region
"El Niño is typically associated with wetter than normal conditions along the southern third of California eastward following the U.S.-Mexico border and drier than normal conditions in the Inland Northwest and northern Rockies. El Niño is not usually a good predictor of winter precipitation for northern California and the northern Great Basin, though model simulations suggest a very strong El Niño may drive above normal precipitation in this area and further north."
El Niño Impacts and and Outlook: Southern Plains Region
"In the south-central United States, there are typically four major impacts during an El Niño event. These consist of:
- above normal precipitation, particularly during winter
- below normal temperatures, also during winter
- a less active hurricane season, with fewer named storms
- a slightly higher probability of snowfall and sleet events"
El Niño Impacts and and Outlook: Midwest Region and Great Lakes Region
"This pattern brings above-normal temperatures to much of the Midwest region, particularly across the northern states. This does not mean that cold weather will not happen this winter but typical extreme cold weather may be milder and less frequent. In addition, this pattern may bring drier conditions to eastern portions of the Midwest. Warmer conditions may reduce total snowfall and the frequency of heavy snowfall events in the Midwest. However, a potentially more active storm track across the southern U.S. poses an increased risk of heavy snow events across the lower Midwest."
"Warmer conditions may reduce total snowfall in the basin and lead to minimal ice cover on the Great Lakes this winter. In addition, the above-normal temperatures will likely reduce the amount of snowpack accumulation in the season."
El Niño Impacts and and Outlook: Eastern Region
"This pattern brings above-normal precipitation to southern parts of the Eastern Region, as the Pacific jet stream steers storms along the Gulf and southeast Atlantic coasts. The active Pacific storm track also promotes cloudy conditions in the Southeast, resulting in cooler-than-normal temperatures over the southern portions of the Eastern Region. It is more difficult to define conditions in the northern sections of the Eastern Region because of other atmospheric and oceanic influences. The dry winter conditions that characterize Ohio and the Midwest extend eastward, with drier-than-normal conditions common in western New York and Pennsylvania. As storms often move up the coast during El Niño winters, the Eastern Seaboard generally experiences above-normal precipitation."
El Niño Impacts and and Outlook: Southeast Region
"A pronounced gradient in precipitation is typically observed across the Southeast during El Niño, with above-normal precipitation in southern and southeastern portions of the region. Average or drier-than-normal conditions are generally found across the interior northwestern portion of the region, which is less influenced by the southerly storm track.
Cooler-than-average temperatures usually occur across the Gulf Coast region during El Niño, with near-normal temperatures to the north. Daily maximum temperatures are typically below average across the southern portion of the region, while daily minimum temperatures are often near average or even slightly above average."
El Niño and Its Impacts on the Hawai'ian Islands
"Rainfall during the developing El Niño starts out much wetter than normal, especially from August through October. By November, a rapid decline in rainfall begins, sinking to well below average by February of the following year. The level of these dry conditions depends on the intensity of the El Niño event, though widespread dryness across the Hawai'ian Islands is typical. Rainfall returns to normal by July of the year following an El Niño event."
- Regional El Niño Impacts and Outlooks Assessments (Website) National Oceanic and Atmospheric Administration
A webpage with a description of the current status of El Niño and links to downloadable regional El Niño Impacts and Outlooks Assessments.
- El Niño Portal (Website) National Oceanic and Atmospheric Administration
A portal for information on the current state of El Niño and links to primers and videos about El Niño and La Niña.
- Learn More About El Niño/La Niña (Website) National Aeronautics and Space Administration
Basic descriptions of El Niño and La Niña and a wealth of links to additional information and images