Boston/Logan Intl climate by month
Averages and records for each calendar month at Boston/Logan Intl, United States, from 1936 to 2026. The warmest month is July, averaging 27.8°C; the coolest is January at 2.5°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 2.5°C | −5.2°C | 23.3°C12 January 2020 | −24.4°C15 January 1957 | 91 / 91 |
| February | 3.6°C | −4.5°C | 22.8°C24 February 2017 | −25.6°C15 February 1943 | 91 / 91 |
| March | 7.6°C | −0.5°C | 31.7°C31 March 1998 | −17.2°C5 March 1948 | 91 / 91 |
| April | 13.5°C | 4.7°C | 34.4°C18 April 1976 | −8.9°C7 April 1982 | 91 / 91 |
| May | 19.4°C | 10.1°C | 35.6°C31 May 1944 | 1.1°C16 May 1936 | 91 / 91 |
| June | 24.7°C | 15.2°C | 38.9°C24 June 2025 | 5.0°C1 June 1945 | 91 / 91 |
| July | 27.8°C | 18.7°C | 39.4°C22 July 2011 | 10.0°C1 July 1988 | 91 / 91 |
| August | 26.8°C | 18.1°C | 38.9°C2 August 1975 | 7.8°C25 August 1940 | 91 / 91 |
| September | 22.7°C | 14.1°C | 37.8°C2 September 1953 | 2.8°C27 September 1947 | 90 / 91 |
| October | 17.0°C | 8.5°C | 32.2°C12 October 1954 | −3.9°C27 October 1936 | 90 / 90 |
| November | 11.1°C | 3.3°C | 28.3°C2 November 1950 | −11.1°C26 November 1938 | 90 / 90 |
| December | 5.1°C | −2.4°C | 24.4°C7 December 1998 | −23.9°C20 December 1942 | 90 / 90 |
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 90 to 91 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.