The climate of the Midwest has changed over time since the beginning of modern records in 1895. Presented here are maps of the state average annual and seasonal temperature and precipitation trends between 1895 and 2010. Temperature trends are shown in degrees Fahrenheit change per century, and precipitation trends are reported as inches of precipitation change per century. The monthly state average data used to calculate the trends came from the National Climatic Data Center. Click an image to see a larger version.
How the Trend Values Were Calculated: The values displayed on the maps are linear trends in units per century. Monthly data for each state was averaged (temperature) or totaled (precipitation) into seasonal or annual values. Linear regressions were computed from the seasonal and annual data. The resulting regression coefficients (slopes) were multiplied by 100 to compute the changes per century which are displayed on the maps.