The coldest air of the season so far visited the state this week with sub 0°F wind chill readings found on Wednesday into Thursday. Is such cold readings this early in the season common? The featured chart presents the IEM computed minimum wind chill temperature for Des Moines each year between 1 October and 5 December. This year's value of negative ten degrees is a bit colder than the long term simple average for this period, but only at about the 70th coldest percentile. A 30 year moving average is fit to the yearly data and does show a recent warming trend with this value. Please note that the wind chill value for the entire archive is using the present day NWS equation, so we are generally comparing apples to apples outside of some observation differences with wind speed that are likely biasing the old data colder.

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