From NWS
1999: Several rounds of thunderstorms dropped heavy rain across portions of northeastern Iowa from July 18-20 and into early morning on the 21st. Rainfall totals during this time included 10.75 inches at Osage, 11.81 inches at Charles City, and 11.85 inches at New Hampton. In just 24 hours ending on the morning of the 21st New Hampton recorded 7.10 inches of rain, while Charles City received 6.65 inches which is just 0.01 inches shy of the all-time 24 hour record at that location. Nearly all creeks, streams, and rivers in Chickasaw, Floyd, Mitchell, and Howard counties were sent above bankfull with record flooding occurring at some locations. The Cedar River inundated more than 100 homes in Charles City, washed out many roads across the area, and closed down portions of Highway 218. The river gauge at Charles City even went underwater with the river cresting at an estimated 22.80 feet on the 21st, making it the highest crest on record at that location until the record shattering floods of June 2008. Additional flooding occurred further downstream at Nashua where the water topped the dam at Cedar Lake flooding nearby homes and parts of the downtown area. Elsewhere the Wapsipinicon River expanded to nearly a mile wide in some places, closing sections of several state highways.

21 July 1983 → Vostok, Antarctica recorded the coldest temperature ever on the planet: 129 degrees below zero. 21 July 1987 → An F4 tornado swept through Yellowstone National Park leaving a path of destruction up and down a 10,000 ft mountain, the highest elevation an F4 has been recorded. 15,000 acres of trees were downed.

Posted under Weather History