Where Is The Most Unpredictable Weather Found in The U.S.?

So who has the craziest weather in the United States?  One study, conducted by FiveThirtyEight Science, aimed to find out through the help of the 120 National Weather Service offices across the country.  Data was collected over the last two decades.  Daily weather patterns against long-term averages were used to come up with a result. Weather, at least in this case, is defined as being more unpredictable when it deviates more from these long-term trends.  The statistics fall into three categories...temperature, precipitation, and severe weather.

It was discovered Rapid City, South Dakota (Index of 84) is the most unpredictable while Phoenix, Arizona is the least (Index of 38).  Milwaukee is in the Top 50 (Index of 47) of unpredictability while Chicago has a \"better\" ranking at 58. 

Overall, ten weather conditions were translated onto a common scale where 66 represents average.  For example, the high temperature for the 120 weather stations tracked was about 66 degrees on average throughout the year.  The collection of data was day-to-day, not hour-to-hour.