Mariehamn weather in August
In August, Mariehamn has daytime highs averaging 18 °C, nights around 15 °C, with 9.9 wet days, and a sea temperature of 17 °C. Figures are 1991–2020 climate normals.
- 18.4°C Average high
- 15.2°C Average low
- 9.9days Wet days
- 55mm Rainfall
- 16.7°C Sea temperature
- 16h Daylight
Daily temperatures through August
How August develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 August | 19.4 °C | 16.0 °C | 29 % |
| 11–20 August | 18.4 °C | 15.2 °C | 33 % |
| 21–31 August | 17.5 °C | 14.4 °C | 32 % |
- Average highs fall from 19.4 °C early in August to 17.5 °C by the end of it.
What to expect
| Measure | Typical August | Share of the month |
|---|---|---|
| Days above 25 °C | 0.1 of 31 | 0 % |
| Days above 30 °C | 0 of 31 | 0 % |
| Days below 0 °C | 0 of 31 | 0 % |
| Days with more than 1 mm rain | 9.9 of 31 | 32 % |
Conditions in August
| Measure | Average |
|---|---|
| Mean temperature | 17 °C |
| Record high (1991–2020) | 26 °C |
| Record low (1991–2020) | 8.6 °C |
| Relative humidity | 78 % |
| Wind speed | 21 km/h |
| Cloud cover | 57 % |
Where Mariehamn ranks in August
| Ranking | Position | Value |
|---|---|---|
| The coolest places in Europe in August | 27thof 50 | 18 °C |
August compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| June | 14.7 °C | 50 mm | 54 % |
| July | 18.6 °C | 52 mm | 52 % |
| August | 18.4 °C | 55 mm | 57 % |
| September | 14.3 °C | 47 mm | 60 % |
| October | 9.1 °C | 51 mm | 70 % |
See all twelve months for Mariehamn
- August is the 2nd warmest month here.
- It is the 12th driest month of the year.
- It ranks 4th for least cloud cover.
- Days last about 16 hours from sunrise to sunset.
- It rains on 9.9 of 31 days — 32 % of the month.
- Nights are about 3.2 °C cooler than the middle of the day.
- The hottest August day on record since 1991 reached 26 °C, 7.7 °C above the usual daytime high.
- Beach score: 36 / 100 — see how this is calculated.
Nearby destinations in August
| Destination | Avg high | Wet days | Sea |
|---|---|---|---|
| Mariehamn | 18 °C | 9.9 | 17 |
| Uppsala | 21 °C | 12 | – |
| Stockholm | 20 °C | 11 | 17 |
| Turku | 20 °C | 12 | – |
| Tampere | 19 °C | 13 | – |
QuestionsAugust in Mariehamn, answered
How warm is Mariehamn in August?
Daily highs average 18 °C and nights fall to about 15 °C, a spread of 3.2 °C between afternoon and dawn. That makes August the 1st warmest month of the year here.
Does it rain much in Mariehamn in August?
August averages 55 mm of rain, spread over about 10 of the 31 days — 32 % of the month. Cloud cover averages 57 % of the sky.
Is the sea warm enough to swim in August?
The sea averages 17 °C off Mariehamn in August. Most people find water below 20 °C bracing and above 25 °C comfortable for a long swim; this figure is a monthly surface average, so a sheltered bay on a still afternoon can be warmer.
How long are the days in August?
Mariehamn averages 16 hours between sunrise and sunset in August. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.