Weather in Mariehamn

Planning your day in Mariehamn? Here you will find the most up-to-date weather information, including forecasts and useful charts, to ensure your stay is as comfortable as possible.

The climate of Mariehamn is characterised by distinct seasonal changes, with noticeable temperature fluctuations throughout the year. Overall, it can be described as temperate with maritime influences, resulting in relatively mild temperatures for northern latitudes, although winters here are still cold. The city experiences cool, and at times frosty, winters and moderately warm, pleasant summers.

Winters in Mariehamn (from December to March) are cold, with average temperatures around 0°C, often dropping below freezing. Summer (from June to August) offers more comfortable weather, with average temperatures around 15-17°C and maximum highs reaching 20°C. Spring and autumn are transitional seasons with gradual temperature changes. One of the notable features of Mariehamn's climate is the low level of precipitation throughout the year, usually not exceeding 1-2 mm per month. Despite this, the number of days with precipitation can be quite significant, especially during the autumn-winter period, indicating frequent but light precipitation, such as drizzle or light snow.

The climate in Mariehamn is characterised by pronounced seasonal temperature variations. The annual temperature progression shows that the coldest month is February, when the average temperature is around -0.5°C, and minimum values can drop to -2.2°C. Conversely, the warmest period falls in July, when the average temperature reaches 17.3°C, and daily highs average 20.1°C. August is also very warm, with an average temperature of 17.2°C, making summer in Mariehamn a pleasant time of year.

The summer months, from June to August, in Mariehamn are distinguished by comfortable and moderately warm weather. Average daytime temperatures during this period range from 18.2°C in June to 20.1°C in July, while night-time temperatures usually stay within the range of 11.8°C to 14.8°C. Such weather is conducive to walking and outdoor activities without exhausting heat. The difference between day and night temperatures in summer is approximately 5-6°C, which is a moderate indicator.

The winter period in Mariehamn, from December to February, is quite cool but without extreme frosts. Average temperatures during these months hover around zero: from 1.3°C in December to -0.5°C in February. At night, the temperature regularly drops below freezing, reaching -1.4°C in January and -2.2°C in February, while during the day it is usually slightly above the freezing point. Daily temperature fluctuations in winter are less pronounced than in summer, amounting to about 2-3°C. Spring and autumn are transitional seasons with a gradual rise or fall in temperature, with April and October showing average temperatures of 4.0°C and 8.6°C respectively.

In Mariehamn, there is no clearly defined rainy season in terms of total rainfall volume, as only 1-2 mm falls monthly. However, the frequency of days with precipitation varies noticeably throughout the year, allowing for the distinction between wetter and drier periods.

The highest number of days with precipitation occurs during the autumn-winter period. December is the "wettest" month, averaging 16 days with precipitation. It is followed by October (about 14 wet days) and January (about 13 wet days). Given the low average temperatures in these months (January 0.1°C, February -0.5°C, December 1.3°C), precipitation in winter often falls as snow or sleet. In March, with an average temperature of about 0.7°C, snowfall is also possible, especially at the beginning of the month, or mixed precipitation.

The "driest" months in terms of precipitation frequency are May and June, each averaging only 6 days with precipitation, despite the total moisture volume (1 mm) being comparable to some other months. April is also relatively dry, with 8 rainy days. In summer months, such as July and August, precipitation amounts to about 2 mm, distributed over roughly 10-12 days and falling predominantly as rain.

Overall, Mariehamn is characterised by frequent but not overly intense precipitation. Travellers should be prepared for the likelihood of precipitation at any time of the year. This is especially true for the period from October to January, when days with precipitation are most frequent, and may include snow, particularly from December to February. Summer offers more days without precipitation, but light rain remains a possibility.

When planning a trip to Mariehamn, it is important to consider the changeable weather and frequent precipitation in the form of light rain or drizzle, which is characteristic of this region throughout the year. The key principle when packing your suitcase is layering: this will allow you to easily adapt to changes in temperature and comfort levels. Be sure to bring comfortable waterproof walking shoes, as the number of days with precipitation is quite high even with a small total volume. A light waterproof and windproof jacket or a compact umbrella will be your trusty companions in almost any season.

In the cold season, roughly from October to April, when the average temperature hovers around zero degrees Celsius and can drop lower, focus mainly on warm clothing. This could include thermal underwear, fleece jackets, a warm sweater, as well as a winter jacket that is wind and moisture resistant, a hat, a scarf, and gloves. For the summer months, from June to August, when the air warms up to an average of +15...+17°C, lighter items are suitable: t-shirts, shorts, and light trousers. However, even in summer, do not forget about the potential coolness in the evenings or windy weather, so a light jumper or windbreaker will not go amiss. In May and September, the weather is transitional, so layering is particularly relevant. Don't forget sunscreen for clear summer days.