WASHINGTON NATIONAL AIRPORT weather by month
Averages and records for each calendar month at WASHINGTON NATIONAL AIRPORT, United States, from 1941 to 2026. The warmest month is July, averaging 31.3°C; the coolest is January at 6.5°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 6.5°C | −1.8°C | 26.7°C26 January 2024 | −20.6°C17 January 1982 | 85 / 85 |
| February | 8.4°C | −0.9°C | 27.8°C28 February 1948 | −15.6°C2 February 1961 | 85 / 85 |
| March | 13.4°C | 3.2°C | 31.7°C29 March 1945 | −11.7°C4 March 1943 | 85 / 85 |
| April | 19.5°C | 8.3°C | 35.0°C23 April 1960 | −4.4°C14 April 1950 | 85 / 85 |
| May | 24.4°C | 13.8°C | 37.2°C31 May 1991 | 1.1°C9 May 1947 | 85 / 85 |
| June | 29.1°C | 18.9°C | 40.0°C29 June 2012 | 8.3°C6 June 1945 | 85 / 86 |
| July | 31.3°C | 21.6°C | 40.6°C7 July 2012 | 12.2°C1 July 1988 | 86 / 86 |
| August | 30.3°C | 20.8°C | 40.6°C17 August 1997 | 9.4°C29 August 1986 | 86 / 86 |
| September | 26.6°C | 17.0°C | 38.3°C2 September 1980 | 3.9°C24 September 1963 | 85 / 86 |
| October | 20.6°C | 10.5°C | 36.7°C2 October 2019 | −1.7°C24 October 1969 | 85 / 85 |
| November | 14.4°C | 4.8°C | 30.0°C1 November 1974 | −8.9°C29 November 1955 | 85 / 85 |
| December | 8.5°C | 0.2°C | 26.1°C7 December 1998 | −17.2°C21 December 1942 | 85 / 85 |
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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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.