Mariehamn Weather in September
Mariehamn in September sees moderate daytime temperatures of 16°C (61°F) and nighttime lows of 12°C (54°F). Moderate rainfall is typical, with around 59 mm (2.3 in) for the month.
Rainfall in Mariehamn in September
Historically, September sees about 16 days of rain, with a monthly average of 59 mm (2.3 in). Rain is frequent but mostly light this month, with brief showers more common than heavy downpours.
Temperature in Mariehamn in September
If you're visiting Mariehamn in September, expect highs of 16°C (61°F) and overnight lows around 12°C (54°F). Summer occurs in September. Conditions are often most pleasant around the middle of the day. With lows of 12°C (54°F), nights are cool. If you're out after dark, an extra layer will keep you comfortable. The cooler air at night is also great for getting a good rest.If you prefer dry days with pleasant temperatures, July and August typically offer the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Finland, check out our Mariehamn's climate page.
Mariehamn Temperature in September
Min Temperature
12°C (54°F)
Max Temperature
16°C (61°F)
Chance of Rain
52%
Precipitation
59 mm (2.3 in)
Rainy days
16 days
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Mariehamn typically drop from around 17°C (63°F) at the start of September to approximately 12°C (54°F) by the end. Nights are cool, with lows typically ranging from 6°C (43°F) to 11°C (52°F).
Average temperatures in September
Historical weather for Mariehamn in September
Browse day-by-day weather records for Mariehamn spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Mariehamn historical weather extremes in September
According to our 49 years of weather records for Mariehamn, the following extremes were recorded between 1976 and 2025.
- On September 5, 2024, temperatures climbed to 25°C (77°F), marking the warmest September day on record.
- On September 26, 1986, Mariehamn saw its coldest September day with temperatures maxing out at 6°C (43°F).
- Nighttime temperatures dropped to -5°C (23°F) on September 30, 1976, marking the coldest September night on record.
Best Places in Finland in September
Find out more about the weather in Finland and which places have the best travel conditions in this month. See all of Finland in September →
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What to Wear in Mariehamn in September
Pack for changing conditions in Mariehamn in September. Bring a mix of short and long sleeves, a warm layer like a hoodie or light jacket, and comfortable pants. The key is being able to add or remove layers as the days goes by. Rain gear is recommended, you can expect wet weather on multiple days.What To Do in Mariehamn in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Finland, check out our Mariehamn's climate page.
See the full Mariehamn climate overview or explore weather in Finland.
