Portland/Hillsboro Arpt weather by month
Averages and records for each calendar month at Portland/Hillsboro Arpt, United States, from 1998 to 2026. The warmest month is August, averaging 28.2°C; the coolest is December at 7.8°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 8.3°C | 0.9°C | 17.8°C18 January 2005 | −16.0°C13 January 2017 | 28 / 28 |
| February | 10.0°C | 0.9°C | 18.9°C11 February 2022 | −8.8°C19 February 2006 | 28 / 28 |
| March | 12.8°C | 2.4°C | 26.1°C25 March 2025 | −6.6°C5 March 2019 | 28 / 28 |
| April | 16.0°C | 3.9°C | 32.2°C28 April 2023 | −3.8°C1 April 2008 | 28 / 28 |
| May | 20.2°C | 7.1°C | 34.4°C22 May 2001 | −1.1°C8 May 2002 | 28 / 28 |
| June | 23.4°C | 9.5°C | 45.6°C28 June 2021 | 1.7°C4 June 2001 | 27 / 29 |
| July | 28.1°C | 11.5°C | 42.2°C21 July 2006 | 3.9°C2 July 2000 | 29 / 29 |
| August | 28.2°C | 11.5°C | 41.7°C14 August 2023 | 3.3°C31 August 2008 | 29 / 29 |
| September | 24.5°C | 8.9°C | 37.8°C2 September 2017 | −1.1°C27 September 1999 | 28 / 29 |
| October | 17.5°C | 5.4°C | 31.7°C8 October 2022 | −6.7°C31 October 2002 | 27 / 28 |
| November | 11.2°C | 2.7°C | 21.1°C3 November 2010 | −9.3°C24 November 2010 | 28 / 28 |
| December | 7.8°C | 0.9°C | 17.2°C4 December 2023 | −15.6°C22 December 1998 | 28 / 28 |
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 27 to 29 years each.
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Climate at nearby stations
The closest stations with twelve months of archive of their own, nearest first.
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.