Mariehamn Arpt climate by month
Averages and records for each calendar month at Mariehamn Arpt, Finland, from 1959 to 2026. The warmest month is July, averaging 20.1°C; the coolest is February at −0.5°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 0.0°C | −5.7°C | 10.9°C6 January 1973 | −32.3°C10 January 1987 | 63 / 64 |
| February | −0.5°C | −6.9°C | 10.4°C23 February 1990 | −32.9°C15 February 1979 | 64 / 64 |
| March | 2.4°C | −4.4°C | 17.0°C27 March 2017 | −25.0°C15 March 1966 | 64 / 64 |
| April | 7.1°C | −0.5°C | 21.1°C30 April 1990 | −18.9°C1 April 1963 | 62 / 63 |
| May | 13.2°C | 3.8°C | 27.1°C16 May 2018 | −6.5°C2 May 1976 | 63 / 63 |
| June | 17.8°C | 8.7°C | 29.4°C29 June 1972 | −2.2°C1 June 1964 | 63 / 63 |
| July | 20.1°C | 11.8°C | 31.0°C28 July 2019 | 1.2°C16 July 1959 | 63 / 64 |
| August | 19.2°C | 11.2°C | 30.7°C6 August 1975 | 0.5°C27 August 1986 | 64 / 64 |
| September | 14.8°C | 7.4°C | 25.7°C5 September 2024 | −6.7°C30 September 1976 | 64 / 64 |
| October | 9.6°C | 3.5°C | 19.0°C4 October 1973 | −11.8°C31 October 1988 | 63 / 63 |
| November | 5.0°C | 0.2°C | 16.6°C6 November 2020 | −20.0°C29 November 2010 | 62 / 63 |
| December | 2.0°C | −3.4°C | 11.1°C6 December 2015 | −28.9°C31 December 1978 | 61 / 63 |
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 61 to 64 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.