How can we say with certainty that Minnesota's climate has changed over the last century? It's largely because of daily weather observations from dozens of stations around the state that, in some cases, date back to the late 1800s. Those observations provide millions of data points.
While gaps in the data records and other flaws make tracking trends at any one weather station difficult, climate researchers can combine data gathered from many stations to see what's happening in a region. Minnesota has nine such regions — "climate divisions" as they're officially known.
Click on the maps to see how average temperatures and precipitation totals have changed over time in each region. If you enlarge a graph, hit your browser's "back" button to return to the map.
Note that the dots are scattered all over from year to year — that's normal weather variation — but the trend lines are heading up. That's climate change. You may also note that the more pronounced trend isn't in how warm it gets during the day, it's in how overnight lows are trending up. That affects everything from how seeds germinate to the number of potholes in our roads.
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