Our recent stretch of cool high temperatures was far from where we should be this time of year. One way to measure the distance a temperature is from the average value is to normalize it by the standard deviation for all temperature reports for that day in history. A value of positive two would mean the temperature is two standard deviations warmer than average. By standardizing, we can compare temperatures at most any time of the year. Indeed, the lowest values on the upper air occurred with our recent cool stretch! The bottom chart simply shows the largest and smallest index value per year. The sore thumb in the chart is the -4.3 on December 24, 1983. High temperatures that day were in the negative teens!

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Tags:   highs