Sioux Falls/Foss Fld climate by month
Averages and records for each calendar month at Sioux Falls/Foss Fld, United States, from 1932 to 2026. The warmest month is July, averaging 29.9°C; the coolest is January at −3.6°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | −3.6°C | −14.5°C | 18.9°C24 January 1981 | −37.8°C19 January 1970 | 95 / 95 |
| February | −0.9°C | −12.0°C | 21.1°C23 February 1958 | −35.0°C28 February 1962 | 95 / 95 |
| March | 6.0°C | −5.2°C | 31.7°C21 March 2026 | −30.6°C11 March 1948 | 95 / 95 |
| April | 14.7°C | 1.6°C | 34.4°C25 April 1962 | −15.6°C3 April 1936 | 95 / 95 |
| May | 21.5°C | 8.2°C | 40.0°C30 May 1934 | −8.3°C4 May 1967 | 95 / 95 |
| June | 26.9°C | 14.0°C | 43.3°C21 June 1988 | 0.6°C1 June 1956 | 95 / 95 |
| July | 29.9°C | 17.0°C | 43.3°C17 July 1936 | 3.3°C4 July 1967 | 95 / 95 |
| August | 28.4°C | 15.7°C | 42.8°C24 August 1936 | 1.1°C20 August 1950 | 95 / 95 |
| September | 23.6°C | 10.1°C | 40.0°C6 September 1976 | −5.6°C30 September 1974 | 93 / 94 |
| October | 16.4°C | 3.2°C | 35.0°C1 October 2023 | −12.8°C19 October 1972 | 94 / 94 |
| November | 6.5°C | −4.8°C | 27.8°C6 November 2020 | −27.2°C14 November 1959 | 94 / 94 |
| December | −1.1°C | −11.4°C | 17.2°C1 December 1998 | −33.3°C23 December 1990 | 94 / 94 |
Years shows the number behind the average high, then the number holding a record for that month. They differ because a year contributes an average only when the month has at least 25 days of readings, while a single reading is enough to set a record. The average low is withheld on the same 25-day rule and is counted separately again; it is shown as a dash where the archive cannot support it. Across the twelve months here the averages rest on 93 to 95 years each.
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Every figure on this page is computed from NOAA GHCN-Daily observations stored per station, per year, per month. Nothing is modelled, interpolated or estimated, and a month the archive never covered is left out rather than filled in. A station appears here only once all twelve months carry an average from at least 10 years. See how this is built.