Sunday was incredibly hot and humid over Iowa with afternoon dew point temperatures in the low 80s and air temperatures in the 90s! The featured info-graphic presents IEM computed maximum dew point temperatures on Sunday along with period of record maximums based on unofficial IEM archives of NOAA/NWS data. There are many caveats to this type of analyses as true daily maximum dew point temperatures are not something officially reported nor curated by the NWS. The long term archive is based on mostly hourly reports. Additionally, stations have changed instrumentation, observation techniques, and local surrounding vegetation over the years. All of these items make period of record comparisons problematic. This graphic also is limited to the long term airport sites that are federally maintained. You may have seen other reports about Iowa denoting dew point readings reaching 90°F at state maintained airport stations on Sunday. These values are very likely in error. So having said all of that, three of the listed sites (Ames, Burlington, and Ottumwa) hit period of records on Sunday. Monday will be another very hot and humid day, but hopefully a few degrees less humid than Sunday!