Past Features

This page lists out the IEM Daily Features for a month at a time. Features have been posted on most days since February 2002. List all feature titles.

Thu Oct 01, 2026

High Relative Humidity

The calendar has mercifully turned to October and after the rains end this morning, there is hope for a much needed upcoming stretch of drier weather. Will likely be able to create a number of daily features over the coming days denoting how remarkable the weather of this past September was. The featured chart today looks into daily average relative humidity as computed for the Des Moines Airport weather station. The top panel plots the daily observations along with the climatology which has been smoothed to remove the day to day noise. The bottom panel plots the smoothed frequency of having the daily average relative humidity above 90%. Around 10 days for 2026 are shown having an average relative humidity of 90% or greater, which works out to 30% of the days! The bottom panel puts the climatology around 5% of the days. High humidity and the lack of a killing frost are contributing to significant grain quality concerns as a mature crop continues to wait to be harvested.

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