Black Sunday Turns the Dust Bowl Sky Black
CONFIRMED89% CONFIDENCEThe source[1] fixes the day and tracks the storm across the afternoon: "On the afternoon of April 14, 1935 ... It hit Beaver, Oklahoma, around 4 p.m.; Boise City around 5:15; and Amarillo, Texas, at 7:20." The pin is all-day because the storm crossed several states over one afternoon.
A dust storm swept the Oklahoma and Texas panhandles on the afternoon of 14 April 1935, displacing an estimated 300,000 tons of topsoil. It reached Beaver around 4 p.m., Boise City at 5:15 and Amarillo at 7:20.
Cavendish Laboratory