DULLES INTERNATIONAL AIRPORT weather by month
Averages and records for each calendar month at DULLES INTERNATIONAL AIRPORT, United States, from 1960 to 2026. The warmest month is July, averaging 30.9°C; the coolest is January at 5.4°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 5.4°C | −4.8°C | 26.1°C26 January 2024 | −27.8°C22 January 1984 | 65 / 65 |
| February | 7.5°C | −3.7°C | 26.7°C21 February 2018 | −25.6°C18 February 1979 | 65 / 65 |
| March | 13.0°C | 0.6°C | 31.7°C12 March 1990 | −18.3°C15 March 1993 | 65 / 65 |
| April | 19.1°C | 5.6°C | 33.9°C25 April 1960 | −8.3°C1 April 1969 | 65 / 66 |
| May | 23.8°C | 10.9°C | 36.1°C29 May 1969 | −2.2°C7 May 1970 | 65 / 66 |
| June | 28.5°C | 15.9°C | 38.9°C29 June 2012 | 2.2°C8 June 1977 | 65 / 66 |
| July | 30.9°C | 18.7°C | 40.6°C22 July 2011 | 5.0°C1 July 1988 | 65 / 66 |
| August | 30.1°C | 17.8°C | 40.0°C20 August 1983 | 3.3°C29 August 1982 | 65 / 65 |
| September | 26.2°C | 13.7°C | 37.8°C6 September 2023 | −1.1°C24 September 1974 | 64 / 65 |
| October | 20.0°C | 6.7°C | 35.6°C2 October 2019 | −9.4°C24 October 1969 | 63 / 63 |
| November | 13.8°C | 1.6°C | 28.9°C2 November 1971 | −12.8°C24 November 1989 | 63 / 64 |
| December | 7.8°C | −2.5°C | 26.1°C6 December 1998 | −20.0°C25 December 1989 | 65 / 65 |
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 63 to 65 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.