SeasonMapMariehamn (Aland) weather in September
Åland Islands
September in Mariehamn: cool, a little rain, with clean air — a great time to visit.
#4 of 12 months in Mariehamn · #834 of 1383 destinations to visit in September · comfort 76/100 (tier B)
Updated September 2026 · climate normals from ERA5 reanalysis
Traveller notes on Mariehamn in September
No notes yet. Open Mariehamn on the map to add the first one.
Mariehamn climate normals — September
| Daytime high | 15°C / 58°F | 🙂 cool |
|---|---|---|
| Nighttime low | 12°C / 54°F | |
| Sea temperature | 16°C / 61°F | 🧊 bracing |
| Rainfall | 39 mm / 1.5 in | 🌦 some rain |
| Rainy days | 10 days | |
| Humidity | 79% | 💦 very humid |
| Dew point | 10°C / 50°F | |
| Sunshine | 9 h/day | |
| Daylight | 12.9 h | |
| Wind | 24 km/h / 15 mph | |
| Air quality (US AQI) | 38 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Mariehamn in September
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Shoulder seasonschool holidays in 3 of the markets that fill it, an ordinary month(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Mariehamn's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherMariehamn's weather peaks June–August, best around July.
Best weatherFair weatherToughest weather
What's on in Mariehamn in September
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Opening
Archipelago summer season
15 May – 10 Sep · usuallySummer season opensThe inter-island ferries move to the full timetable, the guest harbours and the Pommern open up, and the cafes on Torggatan put tables outside. Outside this window a lot of it simply is not running. Source ↗
- Festival
Skordefesten harvest festival
15–22 Sep · usuallyFarms, smokehouses and small producers across the islands open their gates for a weekend in the third week of September, with a shuttle bus doing the rounds. It is the last busy weekend of the year here. Source ↗
Nearby, and something's on
Within 300 km of Mariehamn — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Mariehamn?
Mariehamn in September — FAQ
- Is September a good time to visit Mariehamn?
- September in Mariehamn: cool, a little rain, with clean air — a great time to visit. It ranks #4 of 12 months for Mariehamn on SeasonMap's comfort score (76/100).
- What is the weather like in Mariehamn in September?
- In September, Mariehamn averages a daily high of 14.6°C and a low of 12.1°C, with about 38.5 mm of rain over roughly 9.8 rainy days.
- What is the air quality in Mariehamn in September?
- Mariehamn has a mean US Air Quality Index of about 38 in September.
Other months in Mariehamn
Compare Mariehamn in September
Warmer or cooler than Mariehamn in September
Similar destinations in Northern Europe — September
Within 300 km: Stockholm's Crayfish season around 1 Aug – 5 Sep, and Helsinki's Berry and crayfish season around 20 Jul – 10 Sep.