Great Falls Intl climate by month
Averages and records for each calendar month at Great Falls Intl, United States, from 1937 to 2026. The warmest month is July, averaging 29.0°C; the coolest is January at 0.5°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 0.5°C | −10.1°C | 19.4°C31 January 1992 | −38.3°C23 January 1969 | 89 / 89 |
| February | 2.4°C | −8.9°C | 21.1°C27 February 1992 | −37.2°C9 February 1939 | 89 / 89 |
| March | 6.7°C | −5.3°C | 25.6°C29 March 1978 | −35.5°C3 March 2019 | 89 / 89 |
| April | 12.8°C | −0.2°C | 31.7°C20 April 1980 | −22.2°C21 April 2008 | 90 / 90 |
| May | 18.4°C | 4.7°C | 33.9°C21 May 1980 | −11.1°C1 May 2009 | 90 / 90 |
| June | 22.9°C | 8.9°C | 38.3°C30 June 1990 | −0.6°C7 June 1950 | 90 / 90 |
| July | 29.0°C | 12.1°C | 40.6°C10 July 1973 | 2.2°C16 July 1999 | 90 / 90 |
| August | 28.0°C | 11.3°C | 41.1°C5 August 1961 | −1.1°C24 August 1992 | 90 / 90 |
| September | 21.6°C | 6.8°C | 38.9°C3 September 2022 | −11.0°C30 September 2019 | 88 / 90 |
| October | 14.8°C | 1.9°C | 32.8°C3 October 1943 | −23.9°C30 October 1991 | 89 / 89 |
| November | 6.5°C | −4.0°C | 24.4°C5 November 1975 | −31.7°C23 November 1985 | 89 / 89 |
| December | 1.9°C | −8.2°C | 20.6°C5 December 1939 | −41.7°C29 December 1968 | 89 / 89 |
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 88 to 90 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.