Portland Intl climate by month
Averages and records for each calendar month at Portland Intl, United States, from 1940 to 2026. The warmest month is July, averaging 26.2°C; the coolest is January at −0.3°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | −0.3°C | −10.5°C | 19.4°C6 January 2007 | −32.2°C19 January 1971 | 86 / 86 |
| February | 1.1°C | −9.6°C | 20.0°C21 February 2018 | −39.4°C16 February 1943 | 86 / 86 |
| March | 5.4°C | −4.3°C | 31.1°C31 March 1998 | −29.4°C4 March 1950 | 86 / 86 |
| April | 11.7°C | 1.1°C | 33.3°C28 April 2009 | −13.3°C4 April 1954 | 86 / 86 |
| May | 17.6°C | 6.4°C | 34.4°C31 May 1987 | −5.0°C9 May 1956 | 86 / 86 |
| June | 22.8°C | 11.6°C | 37.2°C24 June 2025 | 0.6°C4 June 1944 | 86 / 86 |
| July | 26.2°C | 14.9°C | 37.8°C22 July 2011 | 4.4°C3 July 1962 | 86 / 86 |
| August | 25.5°C | 14.1°C | 39.4°C2 August 1975 | 0.6°C31 August 1965 | 86 / 86 |
| September | 21.2°C | 9.7°C | 35.0°C7 September 1945 | −5.0°C30 September 1941 | 85 / 86 |
| October | 15.2°C | 3.9°C | 31.1°C7 October 1963 | −9.4°C28 October 1976 | 85 / 85 |
| November | 8.8°C | −1.0°C | 26.1°C6 November 2024 | −16.1°C24 November 1989 | 85 / 86 |
| December | 2.4°C | −7.2°C | 21.7°C7 December 1998 | −29.4°C31 December 1963 | 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 85 to 86 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.