SEATTLE-TACOMA INTERNATIONAL AIRPORT weather by month
Averages and records for each calendar month at SEATTLE-TACOMA INTERNATIONAL AIRPORT, United States, from 1948 to 2026. The warmest month is July, averaging 24.4°C; the coolest is January at 7.5°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 7.5°C | 2.0°C | 17.8°C20 January 1981 | −17.8°C31 January 1950 | 79 / 79 |
| February | 9.3°C | 2.6°C | 21.1°C27 February 1968 | −17.2°C1 February 1950 | 79 / 79 |
| March | 11.4°C | 3.6°C | 26.1°C19 March 2019 | −11.7°C4 March 1955 | 79 / 79 |
| April | 14.3°C | 5.4°C | 31.7°C18 April 2016 | −1.7°C21 April 1951 | 79 / 79 |
| May | 18.1°C | 8.3°C | 33.9°C21 May 1963 | −2.2°C1 May 1954 | 79 / 79 |
| June | 21.1°C | 11.0°C | 42.2°C28 June 2021 | 3.3°C12 June 1952 | 79 / 79 |
| July | 24.4°C | 12.9°C | 39.4°C29 July 2009 | 6.1°C4 July 1949 | 79 / 79 |
| August | 24.2°C | 13.1°C | 37.2°C9 August 1960 | 6.7°C4 August 1950 | 79 / 79 |
| September | 21.0°C | 11.2°C | 36.7°C2 September 1988 | 1.7°C27 September 1972 | 78 / 79 |
| October | 15.3°C | 7.7°C | 31.7°C1 October 1987 | −2.2°C19 October 1949 | 78 / 78 |
| November | 10.4°C | 4.4°C | 23.3°C4 November 1949 | −14.4°C15 November 1955 | 78 / 78 |
| December | 7.6°C | 2.3°C | 18.9°C10 December 2014 | −14.4°C30 December 1968 | 78 / 78 |
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 78 to 79 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.