La Niña Impacts 

and Outlook

Great Lakes Region

November 2021

Typical La Niña Winter Pattern

Highlights for the Basin

A La Niña develops when sea surface 

temperatures in the eastern equatorial 

Pacific are consistently cooler-than-average 

for an extended period of time. These cool 

waters affect the location of jet streams, 

which impacts North America. The most 

notable impacts occur in the late winter and 

early spring. 

While no two La Niña events are alike, 

there are some general patterns that are 

predictable. For instance, the polar jet 

stream is typically farther south than usual 

during La Niña winters. This pattern typically 

brings below-normal temperatures to much 

of the Great Lakes region, particularly 

across the western Great Lakes area. The 

southern Great Lakes may also see a slight 

shift toward wetter-than-normal conditions. 

It should be noted the strength of La Niña 

may impact lake ice extent and thickness.

As shown by the thick blue arrow in the above graphic, a typical storm 

path during La Niña tends to track across the northwestern U.S. and dive 

just south of the Great Lakes. This generally means increased chances of 

precipitation for the Northwest, portions of the Great lakes, and the Ohio 

River Valley, with occasional cold air outbreaks across the north.

Image courtesy of the National Oceanic and Atmospheric Administration.

La Niña Outlook

Winter Temperature and Precipitation Outlooks

Valid for December 2021 - February 2022

Temperature Precipitation

The winter temperature outlook (issued in October) indicates that the 

majority of the Great Lakes region has slightly increased chances of 

above-normal temperatures, with higher probabilities in the east. The far 

western portion of the region has equal chances of above-, below-, and 

near-normal temperatures.

The winter precipitation outlook shows a 

slightly increased chance of above-normal 

precipitation for the entire Great Lakes 

region, with higher probabilities over the 

center of the region. Increased precipitation 

may have positive implications, such as 

increased snowpack for winter recreation, 

along with negative impacts like increased 

runoff in the spring. 

A La Niña Advisory is currently in effect, 

which means La Niña conditions have 

developed and are expected to continue. 

Forecasts indicate this La Niña will 

strengthen, peaking as a moderately 

strong event in late fall or early winter. 

According to the NOAA Climate Prediction 

Center, there is an 87% chance that these 

conditions will last through the winter 

and about a 63% chance that La Niña will 

continue into the early spring. 

Images courtesy of the National Oceanic and 

Atmospheric Administration.

Great Lakes Region La Niña Impacts and Outlook | November 2021 

https://www.drought.gov/drought/resources/reports

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

Melissa Widhalm (mwidhalm@purdue.edu)
Potential Winter and Spring Impacts

The image above shows areas that tend to receive more (blue) or less 

(tan) than average snowfall during a La Niña year. The Great Lakes 

tend to have above-normal snowfall during La Niña years.

Agriculture

La Niña winters tend have above-normal snowpack across the Great 

Lakes, which could insulate crops to harsh conditions. Cold outbreaks 

can adversely impact livestock producers due to increased operating 

costs and animal stress. Also, the southern and eastern Great Lakes 

currently has abundant soil moisture, meaning wetter-than-normal 

conditions could lead to delayed spring planting. 

Economy

Cold and wet winters with above-normal 

snowfall can impact some economic sectors. 

Common negative impacts are increases in 

heating costs, snow removal, and difficulties in 

transportation. Sectors that depend on winter 

weather conditions, like winter recreation, 

snow removal businesses, towing companies, 

and road salt sales, will likely see a benefit from 

increased snowfall. More ice on the Great Lakes 

could potentially delay the navigation season for 

shipping in the spring.

Water Levels and Ice

With the increased chances of above-normal 

precipitation, the likelihood of more snow 

accumulation is greater. Increased snowpack 

may lead to a higher chance for more runoff and 

flooding in the spring. The potential for more ice 

later in the winter may result in less evaporation, 

thus keeping lake levels high. Increased runoff 

and decreased evaporation may take less water 

away from the system than normal. These 

factors could lead to higher lake levels.

Comparisons and Limitations

Winter Conditions During Past La Niña Years

The maps above illustrate the late winter (Jan.-Feb.-Mar.) conditions during the 

last La Niña event in 2020-21. Much of the basin was warmer-than-normal (left 

map, orange colors) and precipitation was well below-normal (right map, yellow 

colors). As shown by last year's unexpected pattern, please note that each La 

Niña is different and La Niña impacts may be limited by many factors, including 

long-term trends and being overcome by short-term and local weather events.

While past La Niña events can help inform forecasters about certain conditions, 

there are some limitations. For instance, in the Great Lakes, La Niña is not

known to impact: 1) first freeze in the fall, 2) last freeze in the spring, 3) 

potential for ice storms or blizzards, 4) track or intensity of any single weather 

system, or 5) potential for springtime drought or flooding.

Maps courtesy of the Midwestern Regional Climate Center

Great Lakes Partners

Midwestern Regional Climate Center 

mrcc.purdue.edu

National Oceanic and Atmospheric 

Administration 

www.noaa.gov

 NOAA NCEI 

 www.ncei.noaa.gov

 Great Lakes Environmental Research 

 Laboratory

 www.glerl.noaa.gov

 NWS Climate Prediction Center

 www.cpc.ncep.noaa.gov

 Great Lakes Sea Grant Network 

 www.seagrant.noaa.gov 

 North Central River Forecast Center 

 www.weather.gov/ncrfc

 Ohio River Forecast Center 

 www.weather.gov/ohrfc

Great Lakes Integrated Sciences and 

Assessments 

glisa.umich.edu

American Association of State Climatologists

www.stateclimate.org

National Integrated Drought Information 

System 

www.drought.gov

USDA Midwest Climate Hub

www.climatehubs.usda.gov

Great Lakes Region La Niña Impacts and Outlook | November 2021 

https://www.drought.gov/drought/resources/reports

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

Melissa Widhalm (mwidhalm@purdue.edu)