[6][7] On the morning of August 21, a mid-latitude, deepening low-pressure center moved east-northeastward toward Minnesota, crossing the state during the afternoon and evening.At the time, surface weather data from the Upper Mississippi Valley were sparse, but nearby observations in the afternoon indicated high temperatures in the middle 80s to low 90s °F.[8] As author Joseph Leonard mentioned in the History of Olmsted County, Minnesota, At Rochester the day had been hot with a strong southeast wind, the air was smoky and oppressive, the heavens were overcast with clouds of a dull leaden line, and there were, apparently, three strata, all moving in different directions.[9]Although meteorology in 1883 was primitive compared with modern science, Leonard's observations and other weather reports reveal quite a bit about the atmospheric conditions in Southeastern Minnesota on August 21.[15][6][13] At 9:30 p.m. CDT (02:00 UTC), a final tornado, given an F3 rating upon retrospective review, killed one person and injured 19 others near St. Charles and Lewiston in Winona County.