Historical Weather Patterns of Michigan

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Historical Weather Patterns of Michigan

Evaluating changes in synoptic patterns is tantamount to understanding regional climate change. To date, the synoptic evaluations that have been done regarding climate change output from General Circulation Models have been restricted mainly to examining changes in storm tracks across large areas.

The north generally experiences colder weather compared to the south, but Michigan weather is unpredictable and switches rapidly, especially during the winter (Hodak, 21-28).

Seasons and types of weather--fall, cool nights and warm days; winter--snowy and constantly cold, getting dark early in the evening; spring--warmer days, often rainy with thunderstorms; summer--hot days and warm nights, daylight lasting until late in the evening (Bohnak, 87-95).

People love to talk about the weather. From Maine to the Midwest, locals are convinced that their weather conditions are the weirdest. They'll tell you about the big blizzard, the great flood, or the hideous humidity, convinced that decades of harsh weather have shaped the characters of the local people (Keen, 19-27).

Relationships between springtime heat accumulation and low temperature events in the western Lower Peninsula were investigated. Sixty years (1931-1990) of daily maximum and minimum temperature data from six stations were used to calculate seasonal growing degree day (GDD) accumulation normal and extremes and their relationship to the date of last freeze at each station throughout the period. Results indicate that in spite of a wide range of individual station and year-to-year variability, both regional springtime GDD accumulation thresholds and last freeze dates are occurring earlier but the timing of GDD thresholds is changing more rapidly, resulting in a net trend toward more freezes after certain GDD thresholds are crossed and a flat or increasing amount of GDDs accumulated on the date of last freeze (Keith, 35-41).

Extreme low temperature events are a normal part of springtime climatology in Michigan and can cause severe damage to many of the state's diverse agricultural crops. In particular, late spring freezes are a major concern in the western counties of the Lower Peninsula where commercial fruit production is concentrated and their occurrence may be a significant factor in explaining inter-annual variations of yield (Hodak, 21-28). For example, a series of freezing nights in late May 1992, damaged several types of fruit (grapes, strawberries, plums, and sweet cherries), reducing the overall potential size of the crop. Although United States mean temperatures have been rising during the last decade, perhaps as part of a wider global trend, some recent springs have been particularly warm in Michigan (e.g. 1991), extreme low temperature events continue to occur (Keen, 19-27).

The possible association between regional temperature trends and the risk of extreme minimum daily temperature events has not been widely examined. Some efforts have focused on documenting recent changes in the length of the growing season or on the relationship between mean temperature trends, but little is available concerning Michigan (Keith, 35-41).

Furthermore, recent literature is largely silent on the question of how springtime low temperature risk is conditioned by antecedent weather patterns, that is, for example, whether a warm April is normally followed by a lower-than-average frost risk in May. Regardless, to the extent to which climatological findings of this type could be generalized from one climatic region to another is uncertain, so such relationships established elsewhere might carry very little information about the risk in Michigan (Bohnak, 87-95).

One important relationship between human activities and the atmosphere is pollution. The health effects of polluted air and the ways in which humans and society can reduce pollution are ideas that are considered in the middle and high school benchmarks. At the high school level, in particular, this includes a discussion of global warming and acid rain. Interestingly, one issue for the teaching of these topics is the exclusive connection between air pollution and human activities with lack of regard for other natural sources of air pollution, such as burning leaves, fireplaces, volcanoes and methane gas from cows (Keen, 19-27).

All of the changes are consistent with changes in the general large-scale flow patterns. An understanding of all these synoptic changes provides richness and a more conceptual understanding of how climate change may affect the Great Lakes region.


Bohnak, Karl, So Cold a Sky: Upper Michigan Weather Stories, Cold Sky Publishing, Negaunee, MI, pp. 87-95

Hodak, J. United States Weather: Michigan Edition, U.S. Weather Corp. Oklahoma City, OK. 1976, 21-28

Keen, Richard A., Michigan Weather, Publisher: Two Bears Press, September 1993, pp. 19-27

Keith Heidorn, Keith, And Now...The Weather, Publisher: Fifth House, Jul 13 2005, pp. 35-41