Helena Rgnl climate by month
Averages and records for each calendar month at Helena Rgnl, United States, from 1938 to 2026. The warmest month is July, averaging 29.4°C; the coolest is January at −0.8°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | −0.8°C | −11.8°C | 17.2°C25 January 2015 | −41.1°C25 January 1957 | 88 / 88 |
| February | 2.4°C | −9.2°C | 20.6°C24 February 1995 | −41.1°C2 February 1996 | 88 / 88 |
| March | 7.4°C | −5.2°C | 25.6°C30 March 2004 | −34.4°C25 March 1955 | 88 / 88 |
| April | 13.5°C | −0.4°C | 30.0°C28 April 1939 | −17.2°C2 April 1954 | 89 / 89 |
| May | 18.8°C | 4.6°C | 33.9°C24 May 2001 | −8.3°C2 May 1954 | 89 / 89 |
| June | 23.4°C | 8.8°C | 40.0°C14 June 2021 | −1.1°C13 June 1969 | 89 / 89 |
| July | 29.4°C | 12.0°C | 40.6°C12 July 2002 | 2.2°C7 July 1952 | 89 / 89 |
| August | 28.4°C | 10.9°C | 40.6°C24 August 1969 | −2.2°C25 August 1992 | 89 / 89 |
| September | 22.1°C | 5.9°C | 38.9°C7 September 2022 | −7.8°C14 September 1970 | 88 / 89 |
| October | 14.7°C | 0.3°C | 31.7°C4 October 2024 | −22.2°C30 October 1991 | 88 / 88 |
| November | 5.9°C | −5.9°C | 24.4°C5 November 2020 | −39.4°C16 November 1959 | 88 / 88 |
| December | 0.6°C | −10.3°C | 21.1°C1 December 2021 | −38.9°C17 December 1964 | 88 / 88 |
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 89 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.