Mariehamn climate — normals and trends
Mariehamn (Åland Islands) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 6.3 °C and it receives 568 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is August (16.2 °C on average) and the coldest is February (-2.0 °C). Rainfall peaks in November.
Mariehamn averages 80 frost days, 0 hot days (≥ 30 °C) and 118 rainy days per year.
Mariehamn has warmed by +2.0 °C between 1940 and 2025, or +0.23 °C per decade. This trend is statistically significant.
The number of frost days there went from about 102 to 58 per year over the period.
The hottest day of the period reached 23.8 °C (on 28 July 2018) and the coldest -26.3 °C (on 10 January 1987).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
MariehamnMariehamn
- coords
- 60.10°, 19.93°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
6.3°C
Average daily high
7.4°C
Average daily low
5.4°C
Annual rainfall
568mm
Sunshine / day
7.9h
Mean relative humidity
82%
Average peak wind
32.7km/h
Seasonal range
18.2°C
Frost days (< 0 °C)
80 d/yr
Hot days (≥ 30 °C)
0 d/yr
Rainy days (≥ 1 mm)
118 d/yr
Annual snowfall
87.6 cm
Average feels-like high
3.2 °C
Average feels-like low
0.0 °C
Average peak gust
44.1 km/h
Tropical nights (≥ 20 °C)
1 d/yr
Solar radiation
10.4 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.0 °C
since 1940
+0.2 °C per decade · r² = 0.33 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
23.8 °C
28 July 2018
Coldest day
-26.3 °C
10 January 1987
Wettest day
54 mm
30 May 1942
Windiest day
77.7 km/h
22 February 2002
Strongest gust
116.6 km/h
19 January 1960
Hottest feels-like
27.6 °C
28 July 2019
Coldest feels-like
-35.2 °C
10 January 1987
Snowiest day
15.4 cm
21 March 1974
Sunniest day
17.9 h
27 June 2019
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 2.5 °C | +1.9 °C | 55 mm | +8 mm |
| Feb | 1.1 °C | +1.9 °C | 17 mm | -16 mm |
| Mar | 3.8 °C | +3.2 °C | 6 mm | -23 mm |
| Apr | 6.0 °C | +2.2 °C | 29 mm | -3 mm |
| May | 8.5 °C | +0.9 °C | 26 mm | -6 mm |
| Jun | 13.1 °C | +0.9 °C | 39 mm | -1 mm |
| Jul | 18.4 °C | +1.7 °C | 64 mm | +15 mm |
| Aug | 16.8 °C | -0.3 °C | 69 mm | +7 mm |
| Sep | 15.6 °C | +1.9 °C | 53 mm | -7 mm |
| Oct | 10.8 °C | +2.0 °C | 72 mm | +12 mm |
| Nov | 7.1 °C | +1.9 °C | 41 mm | -24 mm |
| Dec | 6.0 °C | +3.3 °C | 72 mm | +13 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Mariehamn?
Mariehamn has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 6.3 °C and it receives 568 mm of precipitation per year.
What is the hottest day ever recorded in Mariehamn?
The hottest day measured in Mariehamn between 1940 and 2025 was 28 July 2018, reaching 23.8 °C.
What is the coldest day in Mariehamn?
The coldest day measured in Mariehamn between 1940 and 2025 was 10 January 1987, at -26.3 °C.
Does it snow in Mariehamn?
Yes. Mariehamn gets on average 87.6 cm of snow per year and has around 80 frost days.
Has the climate of Mariehamn warmed?
Yes: Mariehamn warmed by +2.0 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Mariehamn?
The wettest day measured in Mariehamn between 1940 and 2025 was 30 May 1942, with 54 mm of rain in 24 hours.
What was the windiest day in Mariehamn?
The windiest day measured in Mariehamn between 1940 and 2025 was 22 February 2002, with winds reaching 77.7 km/h.
What is the warmest month in Mariehamn?
The warmest month in Mariehamn is August (16.2 °C on average); the coldest is February (-2.0 °C).
How much does it rain in Mariehamn?
Mariehamn receives on average 568 mm of precipitation per year, spread over about 118 rainy days.
Is it sunny in Mariehamn?
Mariehamn gets on average 7.9 hours of sunshine per day, roughly 2,884 hours per year over 1940-2025.
What is the biggest single-day snowfall in Mariehamn?
The heaviest 24-hour snowfall measured in Mariehamn between 1940 and 2025 was 21 March 1974, with 15.4 cm.
Are there tropical nights in Mariehamn?
Yes: Mariehamn has on average 1 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Mariehamn?
In Mariehamn, between 1940 and 2025, the highest apparent temperature reached 27.6 °C on 28 July 2019, and the lowest was -35.2 °C on 10 January 1987.
Compare Mariehamn with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Mariehamn