Delta climate by month
Averages and records for each calendar month at Delta, United States, from 1929 to 2026. The warmest month is July, averaging 27.9°C; the coolest is January at −8.1°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | −8.1°C | −19.2°C | 13.3°C30 January 1931 | −39.4°C26 January 1950 | 97 / 97 |
| February | −5.6°C | −17.1°C | 18.9°C26 February 1958 | −43.9°C16 February 1936 | 93 / 97 |
| March | 1.2°C | −10.3°C | 25.6°C27 March 1946 | −36.7°C1 March 1962 | 97 / 97 |
| April | 11.0°C | −1.9°C | 34.4°C26 April 1952 | −23.3°C6 April 2018 | 95 / 96 |
| May | 18.8°C | 5.0°C | 40.0°C30 May 1934 | −11.1°C2 May 1967 | 97 / 97 |
| June | 23.8°C | 10.6°C | 42.8°C17 June 1931 | −1.7°C8 June 1937 | 96 / 96 |
| July | 27.9°C | 13.3°C | 43.3°C7 July 1936 | −1.1°C21 July 1947 | 96 / 98 |
| August | 27.2°C | 11.9°C | 42.2°C5 August 1941 | −1.7°C24 August 1934 | 96 / 98 |
| September | 21.0°C | 6.2°C | 41.1°C8 September 1931 | −11.1°C30 September 1936 | 94 / 97 |
| October | 13.2°C | −0.4°C | 33.3°C2 October 1953 | −20.6°C21 October 1936 | 94 / 95 |
| November | 2.4°C | −8.7°C | 23.3°C1 November 1999 | −30.0°C14 November 1940 | 92 / 95 |
| December | −4.8°C | −15.5°C | 17.2°C7 December 1939 | −38.9°C23 December 1983 | 96 / 97 |
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 92 to 97 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.