February 13, 1938 saw an incredible event in Tri-State weather history. The highest temperature ever recorded in the state of Indiana, 83, was officially recorded near Shoals. Rome saw 82. Other high temperatures included 78 at Mt. Vernon, 77 Fairfield, Harrisburg to 76 at Earlington.
The highest temperatures (80s) tended to occur where the southwest winds blew over a large area of Severe to Extreme short-term drought. The dry soils, with very dry air & sinking motion of the air all contributed to warming. The surface high pumped warmth north, but there was added warmth via the sinking air. The brown color of the soils & vegetation caused a positive warming feedback with all of these other factors.
Henderson, Evansville, Owensboro appear to have been cooler due to recent rainfall & wetter soils at the time.