Waterloo Rgnl climate by month
Averages and records for each calendar month at Waterloo Rgnl, United States, from 1950 to 2026. The warmest month is July, averaging 28.9°C; the coolest is January at −3.5°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | −3.5°C | −13.5°C | 18.3°C26 January 2002 | −36.7°C16 January 2009 | 76 / 76 |
| February | −0.6°C | −10.7°C | 25.6°C26 February 2024 | −35.0°C2 February 1996 | 76 / 76 |
| March | 6.6°C | −4.1°C | 30.6°C29 March 1986 | −36.7°C1 March 1962 | 77 / 77 |
| April | 15.2°C | 2.5°C | 37.8°C22 April 1980 | −20.0°C6 April 1982 | 77 / 77 |
| May | 21.9°C | 9.1°C | 36.1°C27 May 2018 | −5.6°C3 May 2005 | 77 / 77 |
| June | 27.3°C | 14.8°C | 39.4°C21 June 1988 | 3.3°C1 June 1964 | 76 / 76 |
| July | 28.9°C | 17.0°C | 40.6°C31 July 1988 | 5.6°C7 July 1984 | 77 / 77 |
| August | 27.8°C | 15.4°C | 40.6°C17 August 1988 | 0.6°C20 August 1950 | 77 / 77 |
| September | 23.9°C | 10.4°C | 37.8°C3 September 2023 | −5.6°C29 September 1967 | 76 / 77 |
| October | 16.8°C | 4.0°C | 35.0°C6 October 1963 | −11.7°C30 October 1988 | 76 / 76 |
| November | 7.5°C | −3.2°C | 26.7°C8 November 1999 | −27.2°C26 November 1977 | 76 / 76 |
| December | −0.4°C | −9.9°C | 23.3°C15 December 2021 | −33.9°C25 December 2000 | 76 / 76 |
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 76 to 77 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.