- Since 1951, total annual precipitation has increased by 14% in the U.S. Great Lakes region.
- Total annual precipitation will likely continue to increase, but future projections precipitation vary, especially by season.
- Lake effect snowfall will increase until mid-century, afterward there is a projected transition to more winter rain.
- The frequency of lake-effect precipitation may continue to increase in some areas.
- Warming temperatures may cause snowfall to shift to rain in the future.
Disclaimer: The information on this page is currently under internal review to update the text, figures, and citations with more recent information, as well as findings from the U.S. Global Change Research Program Fourth National Climate Assessment (NCA4).
Observed Changes in Precipitation
The frequency, amount, and type of precipitation falling in the Great Lakes region have all changed. Overall, total precipitation has increased by 14% since 1951 in the 8 U.S. Great Lakes states, but trends vary by region. The Upper Peninsula of Michigan, northeastern Wisconsin, and parts of northern Minnesota have seen decreases, while the greatest increases have occurred in the southern Midwest. Changes in precipitation have also been variable by season. Changes in spring and summer precipitation have been highly variable in the center of the Great Lakes region. Fall precipitation has increased more uniformly, and it is the only season in which the Upper Peninsula of Michigan has seen an increase. Winter precipitation has increased in the southern Midwest, roughly consistent with changes in the annual totals.
Projected Changes in Precipitation
Overall, total annual precipitation is anticipated to continue to increase, though models vary widely on the magnitude and seasonal distribution of future changes.1 2 3 4 5 6 Most models project increases during the winter and spring seasons, but models are more varied when looking at the summer and fall.1 7 8 9 10 One analysis indicates a potential 20-30 percent increase in winter and spring precipitation.8 Winter and spring projections indicate the most notable increases up to 30% on average. By contrast, summer and fall projections show little change to slight decreases on average, but individual models vary. Projections often diverge in the summer, with most models showing potential declines in total precipitation and the potential for more consecutive dry days, even as total annual precipitation is projected to increase. Other models project summer precipitation increases in the future. Practitioners may want to consider multiple summertime scenarios to explore uncertainty related to future precipitation events.
Snowfall, Snow Cover, and Snow Depth
Snowfall has increased in northern lake-effect zones in the Great Lakes basin, while snowfall totals in Illinois, Indiana, and Ohio have declined with rising temperatures.11 Warmer Great Lakes surface water temperatures and declining Great Lakes ice cover have likely driven the observed increases in lake-effect snow. As global temperatures continue to rise and further warm the Great Lakes, areas in lake-effect zones may continue to see increasing lake-effect snowfall. Areas in more southern lake-effect zones may see lake-effect snow replaced by lake-effect rain, as winters shorten with warmer temperatures and become less suitable for snow.12 13 14
Snow cover and snow depth in the Great Lakes region are expected to continue to decrease, having already experienced some of the greatest declines of any region in North America.15 Between 1975 and 2004, the number of days with snow on the ground decreased by five days per decade. The average snow depth across the region also decreased by 3 inches (5.1 cm) over the same time period.16
Extreme precipitation events have become more intense and more frequent. Across the eight states in the Great Lakes region, the amount of precipitation falling in the heaviest 1% of precipitation days increased by 35% from 1951 to 2017.
The observed trends of greater frequency and intensity of extreme storm events are projected to continue or accelerate as the effects of climate change become more pronounced.17 18 19 20 21 While the frequency of severe storms such as thunderstorms, heavy rains, and snow may increase, the occurrence of other severe weather events such as hailstorms, tornadoes, and ice storms could decrease or remain unchanged.22 23
- 1. a. b. Walsh, J., and Coauthors, 2014: Climate Change Impacts in the United States: The Third National Climate Assessment. J. M. Melillo, T. C. Richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program.
- 2. Pryor, S. C., D. Scavia, C. Downer, M. Gaden, L. Iverson, R. Nordstrom, J. Patz, and G. P. Robertson, 2014: Chapter 18: Midwest. Climate Change Impacts in the United States: The Third National Climate Assessment, J. M. Melillo, T. C. Richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program, 418-440. 10.7930/J0J1012N.
- 3. Barlage, M. J., P. L. Richards, P. J. Sousounis, and A. J. Brenner, 2002: Impacts of climate change and land-use change on runoff from a Great Lakes watershed. Journal of Great Lakes Research, 28, 568-582.
- 4. Grover, E. K., and P. J. Sousounis, 2002: The Influence of Large-Scale Flow on Fall Precipitation Systems in the Great Lakes Basin. Journal of Climate, 15, 1943.
- 5. McBean, E., 2008: Assessment of impact of climate change on water resources: a long-term analysis of the Great Lakes of North America. Hydrology and Earth System Sciences, 12, 239.
- 6. Wuebbles, D. J., and K. Hayhoe, 2004: Climate Change Projections for the United States Midwest - Climate Change and Environmental Policy. Mitigation and Adaptation Strategies for Global Change, 9, 335-363.
- 7. Argyilan, E., and S. L. Forman, 2003: Lake Level Response to Seasonal Climatic Variability in the Lake Michigan–Huron System from 1920 to 1995. Journal of Great Lakes Research, 29, 488–500.
- 8. a. b. Hayhoe, K., J. VanDorn, T. Croley, N. Schlegal, and D. Wuebbles, 2010: Regional climate change projections for Chicago and the US Great Lakes. Journal of Great Lakes Research, 36, 7-21.
- 9. Schwab, D. J., S. A. Green, H. A. Vanderploeg, J. B. Cotner, B. A. Biddanda, W. C. Kerfoot, and J. W. Budd, 2008: Doughnut in the desert: Late-winter production pulse in southern Lake Michigan. Limnology and Oceanography, 53, 589.
- 10. Weubbles, D. J., 2006: Executive Summary Updated 2005: Confronting Climate Change in the Great Lakes Region. Union of Concerned Scientists.
- 11. Patterson, W. P., A. W. Burnett, H. T. Mullins, and M. E. Kirby, 2003: Increasing Great Lake-effect snowfall during the twentieth century: A regional response to global warming? Journal of Climate, 16, 3535.
- 12. Karl, T. R., J. M. Melilo, and T. C. Peterson, 2009: Global Climate Change Impacts in the United States. USGCRP.
- 13. Kunkel, K. E., N. E. Westcott, and D. A. R. Kristovich, 2002: Assessment of Potential Effects of Climate Change on Heavy Lake-Effect Snowstorms Near Lake Erie. Journal of Great Lakes Research, 28, 521.
- 14. Croley, T. E. I., 2003: Great Lakes Climate Change Hydrological Impact Assessment: IJC Lake Ontario—St. Lawrence River Regulation Study. Technical Memorandum. Water Resources Management Decision Support. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 126, 84.
- 15. Dyer, J., 2006: Spatial variability and trends in observed snow depth over North America. Geophysical Research Letters, 33, L16503.
- 16. Stewart, K. M., P. A. Soranno, V. M. Card, B. J. Benson, M. N. Futter, J. J. Magnuson, and O. P. Jensen, 2007: Spatial analysis of ice phenology trends across the Laurentian Great Lakes region during a recent warming period. Limnology and Oceanography, 52, 2013.
- 17. Changnon, S. A., 2009: Temporal and spatial distributions of wind storm damages in the United States. Climatic Change, 94, 473.
- 18. Changnon, S. A., 2011: Temporal distribution of weather catastrophes in the USA. Climatic Change, 106, 129.
- 19. Changnon, S. A., and N. E. Westcott, 2002: Heavy rainstorms in Chicago: increasing frequency, altered impacts and future implications. Journal of the American Water Resources Association, 38, 1467–1475.
- 20. Hejazi, M., 2009: Impacts of Urbanization and Climate Variability on Floods in Northeastern Illinois. Journal of Hydrologic Engineering, 14, 606.
- 21. Vavrus, S., and J. Van Dorn, 2010: Projected future temperature and precipitation extremes in Chicago. Journal of Great Lakes Research, 36, 22-32.
- 22. Changnon, D., and R. Bigley, 2005: Fluctuations in US Freezing Rain Days. Climatic Change, 69, 229.
- 23. Changnon, S. A., and K. E. Kunkel, 2006: Severe Storms in the Midwest. Illinois State Water Survey Informational/Educational Material 2006-06, Champaign, IL, 74.