Yesterday's featured map displayed the range between the coldest low and warmest high temperature for 2017 over the CONUS. Today's featured chart shows the long term trend of this temperature range by year for Des Moines. Besides the yearly bars representing the temperature ranges, the chart also has long term and recent averages and the trailing 30 year average (yellow highlighted line). That trailing average is rather interesting as it shows a downward trend in range over the past 30 years or so. 2017 bucked this trend somewhat coming in well above the three averages shown.

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