Midwest Region

La Niña Impacts| November 2016 

Contact: Doug Kluck (doug.kluck@noaa.gov) 

La Niña Impacts 

and Outlook

A La Niña develops when sea surface temperatures in the 

equatorial Pacific Ocean are cooler than average for an 

extended period of time. This affects the location of jet 

streams, causing impacts in North America. The most notable 

impacts occur in the winter, when the wind patterns in the 

atmosphere are strongest. 

While no two La Niña events are alike, the typical winter 

weather pattern (image) brings the polar jet stream into Alaska, 

then plunging into the central and eastern United States. This 

path can bring colder-than-normal temperatures into the 

northern United States, especially the northern Rockies across 

the northern plains and into the Great Lakes. Meanwhile, 

the southern Great Plains often are left warm and dry. The 

Pacific jet stream tends to track close to the Pacific Northwest, 

bringing increased chances for moisture there. Finally, odds 

increase slightly for wetter-than-normal conditions in the Ohio 

River valley.

The result for the Midwest is that odds shift toward chances 

to be cooler than normal, especially in upper Midwest to Great 

Lakes area. The Ohio River valley, also may see a slight shift 

toward wetter-than-normal conditions.

Typical La Niña Winter Pattern

Winter Outlook

Climate Prediction Center Precipitation and Temperature Maps La Niña Evolution

La Niña in the Winter

Typical impacts of La Niña on U.S. winter temperature and precipitation. Such impacts 

have been associated with past episodes, but all impacts aren't seen with every episode. 

NOAA Climate.gov drawing by Fiona Martin. (Image Source: NOAA Climate.gov) For more 

information please visit: https://www.climate.gov/news-features/department/enso-blog

Despite the relative weakness of the La Niña, the winter outlook largely follows typical La Niña 

patterns for the Midwest. The Midwest straddles the boundary of temperature conditions, 

with slightly increased chances for colder temperatures to the north and a slightly i Despite the 

relative weakness of the La Niña, the winter outlook largely follows typical La Niña patterns 

for the Midwest. The Midwest straddles the boundary of temperature conditions, with slightly 

increased chances for colder temperatures to the north and a slightly increased chance of warmer 

temperatures across the southern Ohio Valley. Note that these probabilities are quite small 

because of uncertainty in the strength and position of the La Niña as well as other potential 

influences

For precipitation, the typical La Niña pattern indicates wetter than normal conditions possible 

over the Great Lakes into the Ohio River Basin. Equal chances for below-, near-, or above-normal 

precipitation are likely further south and west in the Midwest region. 

The temperature and precipitation outlooks are consistent with a more active storm track across 

the northern portions of the region this winter, leading to more cold outbreaks and precipitation 

chances. Complicating the outlook are the likely weakness of the La Niña, as well as the potential 

for other climate effects (such as the North Atlantic Oscillation) to play a larger role from time to 

time. This and other influences can overwhelm the La Niña pattern and are much more difficult to 

forecast. The La Niña impacts will likely reach their climax early in the winter and then slowly ebb 

as spring approaches. Please visit the Climate Prediction Center at: http://www.cpc.ncep.noaa.gov

La Niña conditions were officially declared in the fall 

of 2016. Conditions strengthened enough to reach 

a weak La Niña phase as predicted when the sea 

surface temperature anomalies surpassed −0.5°C on 

the Oceanic Niño Index (ONI). This La Niña episode 

is not predicted to last very long and the equatorial 

Pacific Ocean may revert back to a neutral condition 

in the later winter. The bar chart shows the likelihood 

of La Niña, El Niño, and neutral conditions over the 

upcoming seasons. The odds are highest for La Niña 

(blue bars) through winter but decreasing. The highest 

odds shift toward neutral (green bars) in early spring 

through the summer months. El Niño (red bars) 

chances increase through the summer as well but 

remain relatively small. This is a typical evolution of 

the ENSO pattern. For more information please visit:

http://iri.columbia.edu/our-expertise/climate

/forecasts/enso/current/

Valid for Dec 

2016–Feb 2017

EC: Equal 

chances for 

above-, below-, 

or near-normal

A: Above normal

B: Below normal

 Midwest

November 2016

Precipitation Temperature
Contact: Doug Kluck (doug.kluck@noaa.gov) Midwest Region

La Niña Impacts | November 2016

Climate Outlooks from NOAA's Climate Prediction Center

Agriculture

La Niña has worldwide impacts to the agricultural sector, 

which can influence markets. More locally the agricultural 

issues are less direct because the major La Niña impact 

occurs in the winter, outside the main growing season. 

Winters associated with La Niña are often colder than 

normal with above average precipitation, which could 

negatively impact any fall seeded crop that must 

overwinter or perennials such as alfalfa or fruit orchards. 

The overall impact is complicated by cold combined with a 

lack of snow cover. Snow cover can protect the crop while 

open conditions under severe cold are more problematic. 

Harsh winter temperatures can be adverse to livestock 

producers through increased operating costs, potential 

stress to animals and snow removal issues. The cold 

would also be beneficial to the large amount of corn being 

stored on the ground this year due to the surplus. Another 

benefit of colder than normal temperatures would be to 

limit certain pests (insects and plants) and diseases.

Economic

Cold and wet winters with above-average 

snowfall can have sector-specific impacts on 

the economy. The largest negative impacts 

associated with La Niña are increases in 

heating costs, costs associated with snow 

removal, and difficulties in transportation. 

Sectors that depend on normal winter 

weather will likely see a benefit from 

increased snowfall. These include winter 

recreation, snow removal businesses, towing 

companies, and road salt sales. Additional 

cold and snow would also hamper winter 

construction in the region.

No Two La Niñas Are the Same

The images below show the differences from 

normal in the last weak La Niña event from the 

winter of 2000–2001 (December–February). In 

many ways the cooler-than-normal temperatures 

and mainly wetter conditions across much of 

the Midwest and Great Lakes is typical. There 

is no guarantee this or anything close to it will 

be the pattern this year. There are limits to our 

predictability of La Niña impacts. As mentioned 

previously short-term climatic influences, that are 

not predictable beyond a week or two, can play 

havoc with the three-month forecasts and can 

overshadow the “typical” La Niña pattern. Even 

the strength of the La Niña (weak versus strong) 

Ecosystems and Rivers

Similar to the potential issues with livestock, 

more severe winter conditions could be 

detrimental to wildlife but beneficial to others 

that depend on very cold temperatures. 

The overall availability to water is complex 

with widely varying soil conditions around 

the Midwest. Early winter precipitation on 

unfrozen soils would be beneficial, while snow 

on the wet soils could add to the potential 

flooding in the spring. With a slight abovenormal in chance for precipitation this winter 

across the upper Midwest, the situation will 

have to be monitored closely for greater 

chances for flooding this spring. 

National Oceanic and Atmospheric Administration

www.noaa.gov

National Weather Service - Central Region

www.crh.noaa.gov/crh

National Centers for Environmental Information

www.ncei.noaa.gov

Climate Prediction Center

www.cpc.ncep.noaa.gov

Midwestern Regional Climate Center

www.mrcc.isws.illinois.edu

National Drought Mitigation Center

www.drought.unl.edu

National Integrated Drought Information System

www.drought.gov

American Association of State Climatologists

www.stateclimate.org

U.S. Department of Agriculture

Regional Climate Hubs

www.usda.gov/oce/climate_change/regional_hubs.htm

International Research Institute for Climate 

and Society

http://iri.columbia.edu

Accumulated Precipitation (%)

12/1/2000–2/28/2001

Departure from Normal Temperature (° F)

12/1/2000–2/28/2001

Images courtesy of: Midwestern Regional Climate Center, Illinois State Water Survey, Prairie Research Institute

University of Illinois at Urbana-Champaign

Midwest Partners 

La Niña can affect some temperature and 

precipitation signals in the region, but it is not 

known to affect:

• First freeze date in the fall (either early or late).

• Last freeze date in the spring (either early or late).

• Potential for ice storms or blizzards.

• Track or intensity of any single weather system.

has an influence on whether temperatures will 

be cold or warm in some cases. Below are some 

additional common limiting factors of La Niña:

• It may not fully develop.

• It may be weak, with little or no discernible 

influence on weather patterns.

• It may be masked by other weather and climate 

signals.

• Single extreme events can “buck the trend” of 

the averages for the rest of the season, with one 

or two high-impact events overshadowing the 

average conditions.

Image courtesy of: Jeff Vanuga, NRCS/USDA

Feeding cattle in winter.

Image courtesy of: Roger HIll, NRCS/USDA

Frost and ice form a conservation barrier.

Image credit: ©iStockPhoto.com/FLDphotos

Traffic jam due to snow.

©iStockPhoto.com/FLDphotos