MENU

NOAA National Centers
for Environmental Information

State Climate Summaries

WISCONSIN

Key Messages   Narrative   Downloads  

Lake Michigan Sunrise 2
Photo by Elvis Kennedy

WISCONSIN

Wisconsin is located in the interior of North America, exposing it to a climate with large ranges in temperature. The southern part of the state experiences cold winters and mild to hot summers, while the north experiences frigid winters and generally cool summers with brief bouts of excessive heat. The lack of mountains to the north or south allows for incursions of bitterly cold air masses from the Arctic, as well as warm and humid air masses from the Gulf of Mexico, further increasing the range of conditions that can affect the state. The winter season is dominated by dry and cold air with occasional intrusions of milder air from the west and south. The summer is characterized by frequent warm air masses, either hot and dry continental air masses from the arid west and southwest, or warm and moist air from the south. However, periodic intrusions of cooler air from Canada provide breaks from summer heat. The state has borders along Lake Superior to the north and Lake Michigan to the east, and the proximity to the lakes provides a moderating effect on temperature for locations along the shorelines. Average annual temperatures vary from 39°F in the north to 50°F in the south.

 

Figure 1

Observed and Projected Temperature Change

VIEW

Observed and projected changes (compared to the 1901–1960 average) in near-surface air temperature for Wisconsin. Observed data are for 1900–2014. Projected changes for 2006–2100 are from global climate models for two possible futures: one in which greenhouse gas emissions continue to increase (higher emissions) and another in which greenhouse gas emissions increase at a slower rate (lower emissions). Temperatures in Wisconsin (orange line) have risen about 2°F since the beginning of the 20th century. Shading indicates the range of annual temperatures from the set of models. Observed temperatures are generally within the envelope of model simulations of the historical period (gray shading). Historically unprecedented warming is projected during the 21st century. Less warming is expected under a lower emissions future (the coldest years being about as warm as the hottest year in the historical record; green shading) and more warming under a higher emissions future (the hottest years being about 11°F warmer than the hottest year in the historical record; red shading). Source: CICS-NC and NOAA NCEI.

Since the beginning of the 20th century, temperatures have risen approximately 2°F and temperatures in the 2000s have been warmer than any other historical period (Figure 1). The period of 2000-2004 was the hottest 5-year period in history. 2012 was the hottest year on record, with a statewide average temperature of 47.4°F, 5°F above the long-term average. This warming has been concentrated in the winter and spring, while summers have warmed less; this is a feature characteristic of much of the Midwest (Figure 2a). Warmer temperatures occurring earlier in the spring presents the additional threat of frost-freeze damage to early budding of fruit trees. In 2012 a “killer frost” closely followed an abnormally warm March resulting in significant damage to fruit crops. The lack of summer warming is reflected in a below average occurrence of very hot days (days with maximum temperature above 95°F) (Figure 2b) and no overall trend in warm nights (days with minimum temperature above 70°F) (Figure 2c). The winter warming trend is reflected in a below average number of very cold days (days with maximum temperature less than 0°F) since 2000 (Figure 3). The increase in winter temperatures has caused reduced lake ice cover. In the Great Lakes, ice coverage in the Great Lakes has been declining since the 1970s. For example, the average annual maximum ice coverage from 2003–2013 was less than 43%, compared to the 1962–2013 average of 52%. Ice cover duration on Lake Mendota has exhibited a consistent downward trend since the late 19th century (Figure 4).

Figure 2

2a

Figure 2a-1

 

2a-1

VIEW

Figure 2a-2

 

2a-2

VIEW
 

Figure 2b

2b

VIEW
 

Figure 2c

2c

VIEW

2d

Figure 2d-1

 

2d-1

VIEW

Figure 2d-2

 

2d-2

VIEW

Figure 2: The observed (a) winter and summer temperatures (1895–2014), (b) number of very hot days (annual number of days with maximum temperature above 95°F) (1900–2014), (c) number of warm nights (annual number of days with minimum temperature above 70°F) (1900–2014) and (d) observed winter and summer precipitation, averaged over 5-year periods. The values in Figures 2a and 2d are from NCEI’s version 2 climate division dataset. The values in Figures 2b and 2c are averages from long-term reporting stations, 28 for temperature and 28 for precipitation. The dark horizontal lines represent the long-term average. Winter and summer precipitation have been above the long term average during the most recent five-year period (2010–2014), with the winter temperatures being their highest on record in recent decades. The number of very hot days have been below the long term average since 1950 (excluding 1984–1988), indicating a lack of summer warming, while the number of warm nights reached the highest level since the 1930s and 40s. Due to extreme drought and poor land management practices, the summers of the 1930s remain the warmest on record. Source: CICS-NC and NOAA NCEI.

 

Observed Number of Very Cold Days

Observed Number of Very Cold Days

Figure 3: The observed number of very cold days (annual number of days with maximum temperature below 0°F) for 1900-2014, averaged over 5-year periods; these values are averages from 28 long-term reporting stations. The number of extremely cold days has varied widely across the historical record. Wisconsin experienced the fewest number of very cold days during the period of 2000-2004, indicative of overall winter warming in the region. Source: CICS-NC and NOAA NCEI.

 

Ice Cover on Lake Mendota

Ice Cover on Lake Mendota

Figure 4: Long-term change in ice-cover duration for Lake Mendota, WI. The total duration of ice cover exhibits a consistent downward trend, decreasing from about 120 days in the late 19th century to less than 100 days in most years since 1990. SOURCE: Wisconsin State Climatology Office

Precipitation varies widely from year to year (Figure 5), and most of the state’s precipitation falls during the warmer half of the year. Statewide annual precipitation has ranged from a low of 20.53 inches in 1910 to a high of 41.28 inches in 1938. Recently, Wisconsin has experienced some unusually wet years; 2010 was the second wettest year on record (39.02 inches), and 2014 was the seventh wettest (37.07 inches). The driest multi-year periods were in the 1890s, 1930s, and mid-1950s, and the wettest in the 1990s and 2000s (Figure 5). The driest 5-yr period was 1929–1933 and the wettest was 1982–1986. Both winter and summer precipitation have been mostly above average over the last 20 years (Figure 2d). The frequency of heavy rain events has increased, with the highest number of 2-inch rain events occurring during the period of 2010–2014 (Figure 6). Snowfall varies from about 30 inches annually in the south to over 100 inches along the Gogebic Range. The heavy snowfall along the Gogebic Range is partially due to lake effect snow events along the south shore of Lake Superior. The shoreline of Lake Superior has experienced significant upward trends in annual snowfall totals. These upward trends are attributed to warmer air temperatures, which results in more moisture availability due to warmer surface water temperatures and reduced lake ice coverage. Annual snowfall totals have also increased over the rest of Wisconsin since 1930.

 

Observed Annual Precipitation

Observed Annual Precipitation

Figure 5: The observed annual precipitation across Wisconsin for 1895-2014, averaged over 5-year periods; these values are from NCEI’s version 2 climate division dataset. Annual precipitation varies widely, but recent years have seen generally above average precipitation. The wettest five-year period was 1982-1986 with an average of 35.69 inches, while the driest period on record (1929–1933) only averaged 27.09 inches. Source: CICS-NC and NOAA NCEI.

 

Observed Number of Extreme Precipitation Events

Observed Number of Extreme Precipitation Events

Figure 6: The observed number of days with extreme precipitation events (annual number of days with precipitation above 2 inches) for 1900-2014, averaged over 5-year periods; these values are averages from 28 long-term reporting stations. A typical station experiences 1 day annually with 2 inches or more of precipitation. Since 1990, Wisconsin has experienced an increasing number of extreme rain events. Source: CICS-NC and NOAA NCEI.

Wisconsin is susceptible to both groundwater flooding, and river flooding, both from ice jams and heavy precipitation, in the many rivers bordering and running through the state. Heavy rain and snow during fall and winter 2007–2008 led to elevated water tables by summer 2008. The elevated water table, combined with enhanced summer precipitation, caused flooding to persist for 6 months, causing approximately $17 mmillion in agricultural and property damage from groundwater flooding alone. In addition, over June 5–12, 2008, a series of storms caused heavy rain to fall across southern Wisconsin, with multiple stations reporting over 10 inches of rain. The rain caused severe flooding, totaling more than $1.2 billion in damages.

Severe winter storms are a regular occurrence due to the state’s northerly location and proximity to the winter storm track. Over February 1–2, 2011, southern Wisconsin experienced blizzard conditions due to a powerful storm tracking south of the state. Snow accumulations ranged from 12–26 inches with wind gusts from 45–60 mph. One of Wisconsin’s worst natural disasters was a devastating ice storm in the south central and southeastern portion of the state over March 4–5, 1976. Ice accumulations of up to 5 inches were reported, downing thousands of power lines and snapping many trees and utility poles. Some rural areas were without power for 10 days.

Severe thunderstorms are a threat to the state, particularly during the spring and summer months. A strong derecho on May 30–31, 1998 caused wind gusts of 70–100 mph, with some areas reporting winds of up to 128 mph. Over 250,000 people lost power, and damages were estimated at over $60 million. Although tornadoes are not as common as in other Midwestern states, they can occasionally occur and cause loss of life. On April 10, 2011, severe thunderstorms caused an outbreak of 15 tornadoes, 4 of which were classified as strong (EF-2 and EF-3). Fortunately, the tornadoes impacted relatively rural areas, limiting damages to just over $10 million.

Water levels in the Great Lakes have fluctuated over a range of three to six feet since the late 19th century (Figure 7). Higher lake levels were generally noted in the latter part of the 19th century and early 20th century, the 1940s and 1950s, and the 1980s. Lower lake levels were observed in the 1920s and 1930s and again in the 1960s. For Lakes Superior and Michigan-Huron, the first part of the 21st century has also seen lower levels. However, rapid increases in water levels have been observed in the Great Lakes following historic lows in 2013. In fact, Lakes Michigan and Huron have experienced a remarkable recovery with a rise of more than 3 feet from low levels in 2013.

 

Annual Lake-Wide Average Water Levels for Lake Michigan-Huron

Annual Lake-Wide Average Water Levels for Lake Michigan-Huron

Figure 7: Annual time series of the water level of Lake Michigan-Huron. Water levels in Great Lakes have varied widely over the years. Lake Michigan-Huron has shown a statistically significant downward trend over the past 150 years. The trend is largely due to the high levels early in the period and extremely low levels during the 21st century. SOURCE: NOAA/NOS and CHS

Under a higher emissions pathway, historically unprecedented warming is projected by the end of the 21st century (Figure 1). Even under a pathway of lower greenhouse gas emissions, average annual temperatures are projected to most likely exceed historical record levels by the middle of the 21st century. However, there is a large range of temperature increases under both pathways, and under the lower pathway, a few projections are only slightly warmer than historical records (Figure 1). Extreme heat is of particular concern when high temperatures, combined with high humidity, can cause dangerous heat index values with resulting risk to human health. Urban areas are especially vulnerable to extreme heat due to the urban heat island effect and high social vulnerability, which can lead to exacerbated health risks. Future heat waves are projected to be more intense; however, cold waves are projected to be less intense. Winter ice cover on the Great Lakes is projected to decrease.

Precipitation is projected to increase for Wisconsin, with the most likely increases occurring during the winter and spring (Figure 8), but snowfall is projected to decline due to the warmer temperatures. Additionally, extreme precipitation is projected to increase, potentially increasing the frequency and intensity of floods. Above normal precipitation raises the risk of springtime flooding, which could pose a threat to Wisconsin’s agricultural industry by delaying planting and resulting in loss of yield.

 

Projected Change in Spring Precipitation

Projected Change in Spring Precipitation

Figure 8: Projected change in spring precipitation (%) for the middle of the 21st century compared to the late 20th century under a higher emissions pathway. Hatching represents portions of the state where the majority of climate models indicate a statistically significant change. Wisconsin is part of a large area of projected increases in the Northeast and Midwest. Source: CICS-NC, NOAA NCEI and NEMAC.

The intensity of future droughts is projected to increase. Even if precipitation increases in the future, increases in temperature will increase the rate of loss of soil moisture during dry periods. Thus, future summer droughts, a natural part of the Wisconsin climate, are likely to be more intense.

Changes in seasonal and multi-year precipitation, evaporation, and temperature can affect water levels in the Great Lakes, causing serious environmental and socioeconomic impacts. During the 1980s high lake levels resulted in the destruction of beaches, erosion of shorelines, and the flooding and destruction of near-shore structures. Low lake levels can affect the supply and quality of water, restrict shipping, and result in the loss of wetlands. Future changes in lake levels are uncertain and the subject of research. Reduced winter ice cover from warmer temperatures leaves shores vulnerable to erosion and flooding.

Lead Authors:
Rebekah Frankson, Kenneth E. Kunkel
Contributing Authors:
Sarah Champion
Recommended Citation:
Frankson, R., K. Kunkel, and S. Champion, 2017: Wisconsin State Climate Summary. NOAA Technical Report NESDIS 149-WI, 4 pp.

Resources

  1. Demaria, E.M.C., J.K. Roundy, S. Wi, and R.N. Palmer, 2016: The Effects of climate change on seasonal snowpack and the hydrology of the Northeastern and Upper Midwest United States. J. Climate, 29, 6527—6541pp, http://dx.doi.org/10.1175/JCLI-D-15-0632.1.
  2. EPA, 2016: What climate change means for Wisconsin, United States Environmental Protection Agency, EPA 430-F-16-051, 2 pp. [Available online at https://www3.epa.gov/climatechange/Downloads/impacts-adaptation/climate-change-WI.pdf]
  3. Gotkowitz, M. B., J.W. Attig, and T. McDermott, 2014: Groundwater flood of a river terrace in southwest Wisconsin, USA, Hydrogeology Journal, 22, 6, 1421—1432. http://dx.doi.org/org/10.1007/s10040-014-1129-x.
  4. Kluver, D. and D. Leathers, 2015. Regionalization of snowfall frequency and trends over the contiguous United States. International Journal of Climatology, 35, 4348-4358.
  5. Kunkel, K.E, L.E. Stevens, S.E. Stevens, L. Sun, E. Janssen, D. Wuebbles, S.D. Hilberg, M.S. Timlin, L. Stoecker, N.E. Westcott, and J.G. Dobson, 2013: Regional Climate Trends and Scenarios for the U.S. National Climate Assessment. Part 3. Climate of the Midwest U.S., NOAA Technical Report NESDIS 142-3, 95 pp. [Available online at https://www.nesdis.noaa.gov/content/technical-reports]
  6. Midwestern Regional Climate Center, cited 2016: “(1981-2010) Maps of gridded data long-term averages; Average Temp — Wisconsin.” [Available online at http://mrcc.isws.illinois.edu/CLIMATE/]
  7. NOAA, 2008: 2008 Midwestern U.S. floods, National Oceanic and Atmospheric Administration National Climatic Data Center, 10pp. [Available online at ftp.ncdc.noaa.gov/pub/data/extremeevents/specialreports/2008-Midwestern-US-Floods.pdf]
  8. NOAA, 2011: April 10, 2011 tornado outbreak: Record April tornado outbreak in Northeast Wisconsin on April 10, 2011, published May 18, 2011, retrieved January 3, 2017, National Oceanic and Atmospheric Administration. [Available online at http://www.weather.gov/grb/041011_tornadoes]
  9. NOAA, cited 2016: Climate at a Glance: U.S. Time Series, published October 2016, retrieved on October 18, 2016, National Oceanic and Atmospheric Administration National Centers for Environmental information. [Available online at http://www.ncdc.noaa.gov/cag/]
  10. NOAA, cited 2016: Climate of Wisconsin, National Oceanic and Atmospheric Administration. [Available online at https://www.ncdc.noaa.gov/climatenormals/clim60/states/Clim_WI_01.pdf]
  11. NOAA, cited 2017: Flooding in Wisconsin, NOAA’s National Weather Service, National Oceanic and Atmospheric Administration. [Available online at http://www.floodsafety.noaa.gov/states/wi-flood.shtml]
  12. NOAA, cited 2017: May 30-31 derecho: “The Southern Great Lakes derecho of 1998”, retrieved January 3, 2017, National Oceanic and Atmospheric Administration. [Available online at http://www.spc.noaa.gov/misc/AbtDerechos/casepages/may30-311998page.htm]
  13. NOAA, cited 2017: Worst snows in the state of Wisconsin from 1881 to present, National Oceanic and Atmospheric Administration. [Available online at http://www.crh.noaa.gov/Image/mkx/pdf/snowstorms-wisconsin.pdf]
  14. Notaro, M., V. Bennington, and S. Vavrus, 2015: Dynamically downscaled projections of lake-effect snow in the Great Lakes Basin, Journal of Climate, 28, 1661-1684.
  15. Ready Wisconsin, cited 2017: Top weather events in Wisconsin for 2011, retrieved January 3, 2017, 15pp. [Available online at http://readywisconsin.wi.gov/news/Top%20Weather%20Events%20in%20Wisconsin%20for%202011.pdf]
  16. Wang, J., X. Bai, H. Hu, A. Clites, M. Colton, and B. Lofgren, 2012: Temporal and spatial variability of Great Lakes ice cover, 1973-2010, Journal of Climate, 25, 4, 1318-1329. [Available online at http://www.crh.noaa.gov/Image/mkx/climate/2012/2012_WI_Yrly_Wx_Summary.pdf]
  17. Wisconsin State Climatology Office, cited 2017: History of freezing and thawing of Lake Mendota, 1852-53 to 2015-16, published March 13, 2016, retrieved January 3, 2017. [Available online at http://www.aos.wisc.edu/~sco/lakes/Mendota-ice.html]
>