BS. You're talking to a lot of people who live in sub-tropical and tropical climates who know how this works. This doesn't happen even in Houston except under very unusual circumstances. In Iowa I am sure there is a time of many summer days when it is 90 degrees and a time of day when the humidity is close to 100%, but those are not the same time of day. The only time this is likely to happen is when the sun back comes out after a huge rain. In general when the temperature goes up the relative humidity goes down. So it may be 75 degrees and 95% humidity around 8:00 AM but when the temperature is 90 degrees at 3:00 PM, the humidity has dropped to maybe 70%. Still high, but not crazy.