Boise Arpt climate by month
Averages and records for each calendar month at Boise Arpt, United States, from 1940 to 2026. The warmest month is July, averaging 33.1°C; the coolest is January at 3.0°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 3.0°C | −5.0°C | 18.9°C31 January 2024 | −27.2°C31 January 1950 | 87 / 87 |
| February | 7.1°C | −2.4°C | 21.7°C29 February 1992 | −26.1°C5 February 1989 | 87 / 87 |
| March | 12.0°C | 0.3°C | 28.3°C20 March 2026 | −14.4°C1 March 1971 | 87 / 87 |
| April | 16.6°C | 3.2°C | 33.3°C25 April 1946 | −7.2°C13 April 1968 | 87 / 87 |
| May | 21.9°C | 7.4°C | 37.8°C31 May 2025 | −5.6°C5 May 1982 | 87 / 87 |
| June | 27.0°C | 11.4°C | 43.3°C28 June 2015 | −0.6°C1 June 1984 | 87 / 87 |
| July | 33.1°C | 15.4°C | 43.9°C19 July 1960 | 1.7°C5 July 1986 | 87 / 87 |
| August | 31.7°C | 14.7°C | 43.3°C4 August 1961 | 1.1°C24 August 1992 | 87 / 87 |
| September | 25.9°C | 10.0°C | 40.0°C7 September 2022 | −5.0°C14 September 1970 | 86 / 87 |
| October | 18.3°C | 4.5°C | 34.4°C1 October 1992 | −11.7°C29 October 1971 | 86 / 86 |
| November | 9.3°C | −0.6°C | 25.6°C6 November 1999 | −19.4°C15 November 1955 | 86 / 86 |
| December | 3.8°C | −4.2°C | 18.3°C22 December 1964 | −31.7°C22 December 1990 | 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.