With a high temperature of 88 degrees on Thursday, Waterloo had one of the warmest readings found in the state. The featured chart presents the daily frequency of Waterloo having a warmer daily high temperature than Des Moines. There's a clear annual signal with an interesting spring season quirk. The lower values during the winter season are likely related to the snowfall and snow cover differences between the two sites with Waterloo having more snow cover on average. The spring season difference is likely a difference in soil types with the area around the Waterloo airport weather sensor having a sandier soil that will warm faster than Des Moines. This effect appears to go away with about a stable value of 30% being established by June, which likely has to do with the establishment of summer time / humid air masses that tend to wash out subtle microclimate differences.

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