Mariehamn in Summer
In summer (June, July and August), Mariehamn sees average daytime highs around 16°C and overnight lows near 14°C, with 151 mm of rain over about 25 wet days across the season. It is the warmest season of the year and the 2nd-wettest season.
Over the season highs climb from about 11°C in early June to 16°C by late August. The sky is clear or mostly clear about 38% of the time across summer, and the air most often feels dry.
Summer is Mariehamn's best season of the year to visit on our travel score. For the whole year in context, see Mariehamn's year-round climate.
- Avg daytime high
- 16°C
- warmest season of the year
- Avg overnight low
- 14°C
- Rainfall
- 151 mm
- 25 wet days
- Avg wind
- 20 km/h
- Travel score
- 5.2
- best season of the year
- Months
- Jun · Jul · Aug
Temperature in Mariehamn in Summer
Over the season highs climb from about 11°C in early June to 16°C by late August.
A typical summer day in Mariehamn reaches about 16°C and drops to 14°C overnight. The warmest of the three months is August, the coolest June.
How summer really feels in Mariehamn
Once humidity and wind are folded in, summer brings about 0 days that feel above 32°C and 0 that feel at or below 0°C.
summer sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
Mariehamn weather by month
How the three summer months (June, July and August) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 2° / -1° | 43 | 10.5 | 8 | 6.4 | 0.0 |
| Feb | 0° / -2° | 29 | 7.7 | 6.5 | 8.6 | 0.0 |
| Mar | 1° / -1° | 27 | 7.1 | 5.1 | 11.3 | 0.0 |
| Apr | 4° / 2° | 29 | 6.9 | 1.7 | 14.2 | 0.0 |
| May | 8° / 6° | 33 | 6.6 | 0.2 | 16.8 | 1.6 |
| Jun | 13° / 11° | 49 | 7.5 | 0 | 18.4 | 3.8 |
| Jul | 17° / 15° | 48 | 7.6 | 0 | 17.7 | 5.9 |
| Aug | 18° / 16° | 55 | 10.2 | 0 | 15.4 | 5.8 |
| Sep | 14° / 13° | 54 | 9.2 | 0 | 12.6 | 4.1 |
| Oct | 9° / 8° | 62 | 11.8 | 0.4 | 9.8 | 1.9 |
| Nov | 6° / 4° | 60 | 13 | 2.9 | 7.1 | 0.4 |
| Dec | 3° / 1° | 56 | 13 | 6.1 | 5.6 | 0.0 |
Cloud cover in Summer
The sky is clear or mostly clear about 38% of the time across summer.
Chance of precipitation in Summer
Mariehamn gets around 151 mm of rain over 25 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 20 km/h across summer.
Sunrise & sunset in Summer
Daylight runs from about 17 h 54 min in early June to 14 hours by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 5.6 kWh/m².
Is summer a good time to visit Mariehamn?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is a reasonable time to visit Mariehamn for sightseeing.
What to pack for Mariehamn in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Mariehamn sees daytime highs around 16°C and nights near 14°C. Pack sun protection. Worth having: a warm layer, rain gear and a windbreaker. About 25 days see rain.
Sea temperature near Mariehamn in Summer
The nearest coast averages about 14°C across summer — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea offshore is warmest in August at about 17°C and coldest in February near 1°C.
The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 2 | 1 | 1 | 3 | 6 | 11 | 16 | 17 | 14 | 10 | 7 | 4 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Cool | Cool | Bracing | Bracing | Bracing | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 2 | Bracing |
| Feb | 1 | Bracing |
| Mar | 1 | Bracing |
| Apr | 3 | Bracing |
| May | 6 | Bracing |
| Jun | 11 | Bracing |
| Jul | 16 | Cool |
| Aug | 17 | Cool |
| Sep | 14 | Bracing |
| Oct | 10 | Bracing |
| Nov | 7 | Bracing |
| Dec | 4 | Bracing |
UV index in Mariehamn in Summer
Clear-sky midday UV across summer averages around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Mariehamn peaks around June 18 at about 5 (high) — a little sun protection helps at midday. It bottoms out near December 20 at about 0 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 4 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 0 | 1 | 1 | 3 | 4 | 5 | 5 | 4 | 3 | 1 | 0 | 0 |
| Level | Low | Low | Low | Moderate | Moderate | High | Moderate | Moderate | Moderate | Low | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 0 | Low |
| Feb | 1 | Low |
| Mar | 1 | Low |
| Apr | 3 | Moderate |
| May | 4 | Moderate |
| Jun | 5 | High |
| Jul | 5 | Moderate |
| Aug | 4 | Moderate |
| Sep | 3 | Moderate |
| Oct | 1 | Low |
| Nov | 0 | Low |
| Dec | 0 | Low |
Where is Mariehamn?
Mariehamn sits at 60.1°N, 19.9°E, 11 m above sea level, in Aland Islands. The nearest listed city is Norrtälje, 78 km away.
Topography around Mariehamn
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Mariehamn.
Within 3 km, the terrain around Mariehamn has only modest variations in elevation — a maximum elevation change of 55 m around an average of 7 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 80 m; within 80 km, only modest variations in elevation — a maximum elevation change of 130 m.
The land around Mariehamn is covered by water (44%) and trees (32%) within 3 km, water (55%) and trees (31%) within 16 km, and water (86%) within 80 km.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Mariehamn (60.0973°, 19.9348°, elevation 11 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.