Mariehamn climate
Mariehamn (Aland Islands) has a warm-summer humid continental climate (Köppen Dfb). The average temperature over the year is 7 °C45 °F, and about 649 mm26 in of precipitation falls in an average year.
Temperature by month
Precipitation by month
Mariehamn climate table
| Month | High °C°F | Low °C°F | Mean °C°F | Precip. mmin | Frost days |
|---|---|---|---|---|---|
| Jan | 133 | −129 | 031 | 532.1 | 19 |
| Feb | 032 | −228 | −130 | 411.6 | 20 |
| Mar | 134 | −130 | 032 | 381.5 | 18 |
| Apr | 541 | 236 | 338 | 361.4 | 3 |
| May | 949 | 643 | 846 | 421.7 | 0 |
| Jun | 1458 | 1152 | 1355 | 582.3 | 0 |
| Jul | 1865 | 1660 | 1763 | 582.3 | 0 |
| Aug | 1865 | 1661 | 1763 | 652.5 | 0 |
| Sep | 1558 | 1254 | 1356 | 602.4 | 0 |
| Oct | 949 | 745 | 847 | 702.8 | 0 |
| Nov | 642 | 439 | 540 | 672.7 | 2 |
| Dec | 337 | 133 | 235 | 622.4 | 9 |
| Year | 1865 | −228 | 745 | 64926 | 71 |
“Year” row: highest monthly high, lowest monthly low, annual mean and annual total. Frost days are for the whole grid cell.
| Month | Humid. | Cloud | Solar | Daylight |
|---|---|---|---|---|
| Jan | 87% | 85% | 0.2 | 6:39 |
| Feb | 89% | 82% | 0.8 | 9:01 |
| Mar | 87% | 71% | 2.3 | 11:34 |
| Apr | 86% | 61% | 4.0 | 14:28 |
| May | 85% | 59% | 5.4 | 17:08 |
| Jun | 82% | 58% | 6.1 | 18:51 |
| Jul | 82% | 61% | 5.6 | 18:06 |
| Aug | 81% | 63% | 4.3 | 15:37 |
| Sep | 83% | 66% | 2.6 | 12:44 |
| Oct | 85% | 77% | 1.1 | 9:57 |
| Nov | 88% | 84% | 0.4 | 7:21 |
| Dec | 87% | 83% | 0.1 | 5:53 |
Humid. = average relative humidity at 2 m; cloud = average cloud amount; solar = average daily solar energy reaching the ground in kWh/m² (all-sky); daylight in hours:minutes, calculated for the 15th of each month.
What the climate of Mariehamn is like
The warmest month is August, with an average high of 18 °C65 °F and a low of 16 °C61 °F. The coldest is February, when highs average 0 °C32 °F and lows −2 °C28 °F. Seasons are strongly marked: the warmest month is on average 18.4 °C33.2 °F warmer than the coldest.
Annual precipitation is moderate at about 649 mm26 in. Rain is spread fairly evenly through the year. The wettest month is October (70 mm2.8 in), the driest is April (36 mm1.4 in).
Relative humidity ranges from 81% in August to 89% in February. The clearest skies (lowest average cloud amount, 58%) are typical of June. Average wind speed near the ground ranges from 15 km/h (10 mph) in May to 24 km/h (15 mph) in December. Daylight lasts from about 5.9 hours in December to 18.8 hours in June.
A lasting snow cover is typical in December–March, when the average snow depth in the reanalysis exceeds 10 cm (deepest in February, about 18 cm).
Best time to visit Mariehamn
Based on these averages, the most comfortable months for sightseeing and outdoor activities are July and August: average highs of 18 °C65 °F to 18 °C65 °F with 58 mm2.3 in to 65 mm2.5 in of precipitation per month.
The most challenging month is February, which is cold, with average highs of 0 °C32 °F.
Comfort score: months are ranked by how close they come to an average high of 21–28 °C (70–82 °F), lows above 5 °C (41 °F), little precipitation and moderate humidity. The best-ranked months of each place are recommended, even where none meets all of these. These are general rules of thumb applied to long-term averages.
What to pack for Mariehamn
- Winter (December–February) — highs 032 to 3 °C37 °F, lows −228 to 1 °C33 °F, about 52 mm2.0 in of precipitation a month. Pack a winter coat, hat, gloves and warm, non-slip boots and shoes with good grip, as frost is common.
- Spring (March–May) — highs 134 to 9 °C49 °F, lows −130 to 6 °C43 °F, about 39 mm1.5 in of precipitation a month. Pack a warm coat, layers and closed shoes.
- Summer (June–August) — highs 1458 to 18 °C65 °F, lows 1152 to 16 °C61 °F, about 60 mm2.4 in of precipitation a month. Pack long sleeves, a sweater and a medium jacket.
- Autumn (September–November) — highs 642 to 15 °C58 °F, lows 439 to 12 °C54 °F, about 66 mm2.6 in of precipitation a month. Pack a warm coat, layers and closed shoes.
How Mariehamn compares
Compared with Uppsala, about 130 km to the west, Mariehamn is on average 0.7 °C1.3 °F warmer and receives 8% less precipitation (649 mm26 in vs 704 mm28 in). The difference is largest in December (4.2 °C7.5 °F warmer).
Places in other countries with the most similar temperature and rainfall pattern: Helsinki (Finland, Dfb), Espoo (Finland, Dfb) and Klaipėda (Lithuania, Dfb).
Nearby places
- Uppsala 130 km · 6 °C44 °F · 704 mm28 in
- Sollentuna 134 km · 7 °C44 °F · 665 mm26 in
- Turku 135 km · 6 °C42 °F · 723 mm28 in
- Stockholm 135 km · 7 °C44 °F · 665 mm26 in
- Västerås 196 km · 7 °C44 °F · 741 mm29 in
- Tampere 261 km · 4 °C40 °F · 776 mm31 in
- Espoo 261 km · 6 °C43 °F · 727 mm29 in
- Helsinki 277 km · 6 °C43 °F · 712 mm28 in
Frequently asked questions
What is the warmest month in Mariehamn?
August is the warmest month in Mariehamn, with an average high of 18 °C (65 °F) and an average low of 16 °C (61 °F).
What is the coldest month in Mariehamn?
February is the coldest month, with an average high of 0 °C (32 °F) and an average low of -2 °C (28 °F).
When does it rain the most in Mariehamn?
October is the wettest month with about 70 mm (2.8 in) of precipitation; April is the driest with about 36 mm (1.4 in).
What is the best time to visit Mariehamn?
Judging by long-term averages, the most comfortable months are July and August.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.