Sioux City/Day Fld climate by month
Averages and records for each calendar month at Sioux City/Day Fld, United States, from 1940 to 2026. The warmest month is July, averaging 30.2°C; the coolest is January at −1.6°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | −1.6°C | −12.6°C | 21.7°C26 January 2002 | −33.2°C2 January 2018 | 86 / 86 |
| February | 1.2°C | −9.9°C | 25.0°C26 February 2024 | −33.2°C15 February 2021 | 86 / 86 |
| March | 8.0°C | −3.7°C | 35.0°C21 March 2026 | −30.0°C5 March 1960 | 86 / 86 |
| April | 16.5°C | 3.0°C | 36.1°C22 April 1980 | −18.9°C3 April 1975 | 87 / 87 |
| May | 22.7°C | 9.6°C | 41.1°C14 May 2013 | −3.9°C3 May 1976 | 87 / 87 |
| June | 28.0°C | 15.3°C | 42.2°C21 June 1988 | 3.3°C4 June 1945 | 87 / 87 |
| July | 30.2°C | 17.8°C | 42.2°C12 July 1995 | 5.6°C30 July 1971 | 87 / 87 |
| August | 28.9°C | 16.5°C | 40.0°C3 August 1947 | 2.8°C20 August 1950 | 87 / 87 |
| September | 24.7°C | 10.9°C | 39.4°C2 September 2000 | −4.4°C29 September 1945 | 86 / 87 |
| October | 18.1°C | 4.1°C | 34.4°C2 October 1997 | −13.2°C27 October 2020 | 86 / 86 |
| November | 8.3°C | −3.6°C | 27.8°C8 November 2006 | −22.8°C14 November 1959 | 86 / 86 |
| December | 0.7°C | −9.9°C | 21.1°C1 December 1998 | −31.1°C22 December 1989 | 86 / 86 |
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 86 to 87 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.