The signs of fall are pretty much everywhere now with even the calendar about to turn into September tomorrow, but the first week of the new month will very much feel like mid summer. The full pull of fall climatology does not arrive for a number of weeks yet as illustrated by the featured map. The map presents the weekly change in high temperature climatology between 31 August to 7 September. Values are rather meager with Iowa shown in the 1 to 2 degrees of cooling over this period. Some of the reasons why summer can stick into September include ample sunshine, elevated humidity levels, active vegetation, and warm soils that take a while to cool off.