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State Climate Summaries

MINNESOTA

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MINNESOTA

 

Figure 1

Observed and Projected Temperature Change

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Observed and projected changes (compared to the 1901–1960 average) in near-surface air temperature for Minnesota. 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 Minnesota (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.

Minnesota is located in the interior of North America, resulting in large temperature variations across the state, where winters are cold in the south and frigid in the north and summers are mild to occasionally hot in the south and pleasantly cool in the north. The lack of mountains to the north or south allows for incursions of bitterly cold air masses from the Arctic as well as warm, humid air masses from the Gulf of Mexico, further increasing the range of conditions that can affect the state. 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 that pushes northward from the Gulf of Mexico. The summer is also punctuated by periodic intrusions of cooler air from Canada, providing breaks from summer heat. Temperature extremes have ranged from as low as -60°F (Feb. 2, 1996, Tower) to as high as 115°F (July 29, 1917, Beardsley). Minnesota’s wide range between highest and lowest temperatures is the third largest of non-mountainous states. Also, Minnesota is located on the eastern edge of the transition zone between the humid climate of the eastern United States and the semi-arid Great Plains, exemplified by large differences in average precipitation across the state. Snowstorms are a normal part of the winter and early spring climate, with average annual snowfall ranging from 40 to 60 inches over most of the state.

Temperatures in Minnesota have increased more than 2°F since the beginning of the 20th century (Figure 1). Since the year 2000, Minnesota has experienced 7 out of its 10 warmest years on record. This warming has been concentrated in the winter while summers have not warmed as much. The summer warming has been mostly an increase in nighttime temperatures, with the coolest nights of summer becoming warmer. By contrast, summer daytime high temperatures have increased very little. This is reflected in a below average occurrence of hot days (maximum temperature above 90°F; Figure 2a). There is no overall trend in warm nights (minimum temperature above 70°F) (Figure 2b). The winter warming trend is reflected in a decline in the number of very cold days (maximum temperature below 0°F) over the past two decades, with a historic low occurring during the 5-year period of 2000 to 2004 (Figure 2c). The date of lake ice-out has also been getting earlier in the last few decades (Figure 3).

Figure 2

Figure 2a

 

Observed Number of Hot Days

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Figure 2b

 

Observed Number of Warm Nights

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Figure 2c

 

Observed Number of Very Cold Days

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Figure 2d

 

Observed Number of Extreme Precipitation Events

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Figure 2: The observed number of (a) hot days (maximum temperature above 90°F), (b) warm nights (minimum temperature above 70°F), (c) very cold days (maximum temperature below 0°F), and (d) extreme precipitation events (precipitation greater than 3 inches), averaged over 5-year periods; the dark horizontal lines represent the long-term average. These values are averages from all available long-term reporting stations (23 each for temperature and precipitation). Since 1990, Minnesota has experienced a below average number of hot days. The number of warm nights peaked during the 1930s, with no long-term trend. Since 1980, the observed number of cold days has been near to below average. The number of extreme precipitation events has been near-normal during the most recent 5-year period (2010–2014). Source: CICS-NC and NOAA NCEI.

Ice-Out Date on Lake Osakis

Ice-Out Date on Lake Osakis

Figure 3: Ice out dates for Lake Osakis, 1867–2016. The dark horizontal line represents the long-term trend. Lake ice out has been getting earlier in the last few decades with three of the five earliest dates occurring since 2000. Source: Minnesota Department of Natural Resources.

Average annual precipitation has been above the long-term average for the past 25 years (Figure 4). Likewise, the number of extreme precipitation events (precipitation greater than 3 inches) has been above the long-term average over the past 30 years, with the record 5-year number occurring during the period of 1990 to 1994 (Figure 2d). Average annual precipitation, including rainfall and the water equivalent found in snowfall, ranges from 18 inches in the far northwest to more than 32 inches in the southeast. Nearly two thirds of the average annual precipitation occurs during the growing season (May through September). However, occasional drought is a natural feature of the climate, occurring when anomalous circulation patterns bring in dry air from the interior of North America.

 

Observed Annual Precipitation

Observed Annual Precipitation

Figure 4: The observed annual precipitation across Minnesota for 1895–2014, averaged over 5-year periods; these values are from NCEI’s version 2 climate division dataset. The driest multi-year periods were in the early 1900s through 1940, and the wettest from the 1990s to the present. The driest 5-year period was 1932-1936 and the wettest were 1982-1986. The dark horizontal line is the long-term average (1895–2014) of 26.2 inches annually. Source: CICS-NC and NOAA NCEI.

Figure 5

Number of Extreme Heat Events by County 1995-2012

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Number of excessive heat events by county from 1995 to 2002. Excessive heat events occur more frequently in counties located in central and southern Minnesota. Source: Minnesota Climate Change Vulnerability Assessment. Data from NCEI’s Storm Events Database.

Between 2000 and 2012, extreme weather events (including extreme drought, summer heat waves, severe storms, heavy rain and flooding, and tornadoes) caused an estimated $4.3 billion in damages to property. In general, thunderstorms cause more property damage than any other extreme weather type in Minnesota. The annual frequency of thunderstorm days is roughly 45 days in the southern part and 30 days along the northern border. Due to Minnesota's northern location, heat waves are infrequent, but they can have severe consequences as the population is less acclimatized to these events. Since 1995, excessive heat events have occurred most frequently in the central and southern counties (Figure 5). Since 2000, the number of very heavy rains (6 inches or more in a day) have been 2-3 times more frequent than in the 20th century.

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. Increases in the number of extremely hot days and decreases in the number of extremely cold days are projected to accompany the overall warming.

Annual average precipitation is projected to increase, with increases most likely occurring in the winter and spring (Figure 6). This is part of a large area of the Northern Hemisphere in the higher middle latitudes projected to see increases. Increases in intense rainfall are also expected. Despite these increases in precipitation, it is possible that future droughts will be more intense because of higher temperatures, which will increase the rate of loss of soil moisture. In 2007, 24 counties in Minnesota received federal drought designations, while 7 counties were declared flood disasters. Again in 2012, 55 counties received drought designations at the same time that 11 counties declared flood emergencies. Recent events demonstrate the likelihood of simultaneous increases in both flooding and drought severity within the state.

 

Projected Change in Spring Precipitation

Projected Change in Spring Precipitation

Figure 6: Projected change in spring precipitation (%) for Minnesota by the middle of the 21st century compared to the late 20th century under a higher emissions pathway. Hatching represents areas where the majority of climate models indicate a statistically significant change. Projected increases in Minnesota are part of a large area of projected increases across the northern United States. Source: CICS-NC, NOAA NCEI, and NEMAC.

Lead Authors:
Jennifer Runkle and Kenneth E. Kunkel
Contributing Authors:
Rebekah Frankson, David Easterling and Sarah Champion
Recommended Citation:
Runkle, J., K. Kunkel, R. Frankson, D. Easterling, and S. Champion, 2017: Minnesota State Climate Summary. NOAA Technical Report NESDIS 149-MN, 4 pp.

Resources

  1. 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]
  2. MDH, 2014:  Minnesota Climate Change Vulnerability Assessment 2014, Minnesota Department of Health, Minnesota Climate & Health Program, Environmental Impact Analysis Unit, 100pp. [Available online at http://www.scribd.com/doc/242864543/MDH-Climate-Change-Vulnerability-Assessment]
  3. MDH, cited 2016: Climate change overview: Climate change in Minnesota climate and health profile report, Minnesota Department of Health. [Available online at http://www.health.state.mn.us/divs/climatechange/climate101.html]
  4. Minnesota Historical Society, cited 2016: Natural disasters in Minnesota, State Historic Preservation Office. [Available online at http://www.mnhs.org/shpo/disaster/disaster2.php]
  5. MN Department of Natural Resources, cited 2016: Climate frequently asked questions. [Available online at http://dnr.state.mn.us/climate/faqs.html]
  6. MN Department of Natural Resources, cited 2016: Climate’s impact on water availability. [Available online at http://dnr.state.mn.us/climate/water_availability.html]
  7. MN EQB, cited 2016: Minnesota and climate change: Our tomorrow starts today, Minnesota Environmental Quality Board. [Available online at https://www.mcknight.org/system/asset/document/664/EQB_Climate_Change_Communications.pdf]
  8. NOAA NCEI, cited 2015: State Climate Extremes Committee (SCEC), Records, National Oceanic and Atmospheric Administration National Centers for Environmental Information. [Available online at http://www.ncdc.noaa.gov/extremes/scec/records]
  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 Minnesota, National Oceanic and Atmospheric Administration. [Available online at https://www.ncdc.noaa.gov/climatenormals/clim60/states/Clim_MN_01.pdf]
  11. Tompkins, F. and C. Deconcini, 2014: The climate change connection to U.S. public health, Fact Sheet, World Resources Institute. [Available online at http://www.wri.org/sites/default/files/WRI14_Factsheets_US_Public_Health_0.pdf]
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