The Iowa Environmental Mesonet (IEM) collects environmental data from cooperating members with observing networks. The data are stored and made available on this website.

IEM Daily Feature

August Weather + Yield

Posted: 25 Aug 2026 05:30 AM, Views: 417
Yesterday's daily feature speculated about the upcoming crop yield impact of low solar radiation days during much of this August. Today's featured chart takes a more direct look into this by comparing various weather summary values over the 1-24 August period for Ames to de-trended corn yield departures for Boone County (the county the weather station resides). The top left panel shows the yearly NASS county corn yield estimates with a number of fits plotted. The red line denotes the simple linear trend and is used to compute a yearly departure value used within all other sub-plots. Eight different yearly weather summary values are plotted against this de-trended yield value. Of note for today is the upper left most plot showing daily average solar radiation as estimated by ERA5-Land. Since long term observations of solar radiation generally do not exist, a model is used to estimate the daily values. At least for this plotted metric, the relationship is not all that exciting as a simple explainer for yield outcomes. As is the general comment for plots in this space, if the relationship was simple/easy, folks would be making a fortune in the futures market!
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Soil Temperatures

Data from the Iowa State Soil Moisture Network is found on this website and daily soil temperature averages are used to produce the highlighted analysis.

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