![]() ![]() The winter warming trend is reflected in a below average number of very cold days since 2000, with a historic low occurring during the 2000–2004 period (Figure 2c). There is no overall trend in warm nights (Figure 2b). By contrast, summer daytime high temperatures have increased very little, which is reflected in a below average occurrence of hot days (Figure 2a). Summer warming has been mostly due to an increase in nighttime temperatures, with the coolest nights of summer becoming warmer. This warming has been concentrated in the winter, while summers have not warmed as much. Since 1998, Minnesota has experienced 8 of its 10 warmest years on record. Temperatures in Minnesota have risen more than 2.5☏ since the beginning of the 20th century (Figure 1). Snowstorms are a normal part of the winter and early spring climate, with annual average snowfall ranging from 30 to 70 inches over most of the state, with higher values near 90 inches along the shores of Lake Superior. The state’s location on the eastern edge of the transition zone between the humid climate of the eastern United States and the semiarid climate of the Great Plains also creates large differences in average precipitation across the state. states, Minnesota has the third-largest range of highest to lowest temperatures. Temperature extremes have ranged from as low as −60☏ (February 2, 1996, at Tower) to as high as 115☏ (July 29, 1917, at Beardsley). The summer is also punctuated by periodic intrusions of cooler air from Canada, providing breaks from the heat. ![]() 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. 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. Minnesota’s location in the interior of North America and the lack of mountains to the north and south expose the state to incursions of bitterly cold air masses from the Arctic in the winter and warm, humid air masses from the Gulf of Mexico in the summer, resulting in large temperature variations across the seasons. Less warming is expected under a lower emissions future (the coldest end-of-century projections being about 2☏ warmer than the historical average green shading) and more warming under a higher emissions future (the hottest end-of-century projections being about 10☏ warmer than the hottest year in the historical record red shading). Historically unprecedented warming is projected during this century. Observed temperatures are generally within the envelope of model simulations of the historical period (gray shading). Shading indicates the range of annual temperatures from the set of models. ![]() Temperatures in Minnesota (orange line) have risen more than 2.5☏ since the beginning of the 20th century. 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). Figure 1: Observed and projected changes (compared to the 1901–1960 average) in near-surface air temperature for Minnesota. ![]()
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