PRECIPITATION RECORDS AT SIOUX FALLS The following are the official top ten heaviest 24 hour precipitation events on record for Sioux Falls... 1. 4.59 inches AUG 1ST 1975 2. 4.54 inches OCT 9TH 1973 3. 4.35 inches MAY 29-30TH 2004 4. 4.32 inches JUN 16-17TH 1957 5. 4.13 inches JUN 6TH 1896 6. 4.04 inches OCT 5TH 1911 7. 4.02 inches SEP 11TH 1966 8. 3.99 inches AUG 31ST 1982 9. 3.96 inches MAY 23RD 1936 10. 3.94 inches AUG 2ND 1959 The following are the greatest 24 hour precipitation events by month for Sioux Falls…in inches melted and by date… JAN 1.61 1-2ND 1960 FEB 2.00 17-18TH 1962 MAR 2.39 25TH 1995 APR 3.72 22ND 2001 MAY 4.35 29-30TH 2004 JUN 4.32 16-17TH 1957 JUL 3.35 1ST 1992 AUG 4.59 1ST 1975 SEP 4.02 11TH 1966 OCT 4.54 9TH 1973 NOV 2.68 23-24TH 2001 DEC 1.44 2-3RD 1955 Note that the most rain ever recorded within the city of Sioux Falls was 7.50 inches in a small part of southwest Sioux Falls between 4 AM and 8 AM on June 16th in 2004. A close second place was 7.46 inches also in southwest Sioux Falls between 4 PM and 7 PM on May 22nd in 1993, which resulted in some of the worst flash flooding in Sioux Falls history.