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

April CDDs


Posted: 24 Apr 2025 05:30 AM, Views: 859
Tags:   cdd  
Wednesday felt a bit like early summer with afternoon temperatures near 80°F, a noticeable increase in humidity, and some festering late afternoon thunderstorms. The featured chart presents monthly Cooling Degree Days (CDD)s for Des Moines since 2006. The start year of the chart has no significance other than to keep the plot legible. CDDs can be computed in a number of ways, but for the purpose of this chart it is simply the average daily temperature minus 60°F and always at least zero in value, so no negative numbers. CDDs are difficult to accumulate during April due to overnight low temperatures typically being well below 60°F and thus pulling the average significantly down. The chart remarkably shows the largest value during the first four month of the year period happening during the epic warmth of March 2012!
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