Mariehamn — Water Temperature in December
Water Temperature Range
-1°C
minimum
4°C
average
7°C
maximum
Water Temperature Chart for Month
The chart shows the average daily water temperature for each day of the month based on historical data.
Table of Water Temperatures by Day of the Month for Previous Years
| Day | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| DEC 1 | 6°C | 6°C | 5°C | 5°C |
| DEC 2 | 5°C | 6°C | 4°C | 5°C |
| DEC 3 | 5°C | 6°C | 4°C | 5°C |
| DEC 4 | 6°C | 6°C | 5°C | 5°C |
| DEC 5 | 6°C | 6°C | 5°C | 5°C |
| DEC 6 | 5°C | 6°C | 5°C | 5°C |
| DEC 7 | 5°C | 5°C | 4°C | 5°C |
| DEC 8 | 5°C | 5°C | 4°C | 4°C |
| DEC 9 | 4°C | 5°C | 4°C | 4°C |
| DEC 10 | 4°C | 5°C | 4°C | 4°C |
| DEC 11 | 5°C | 5°C | 4°C | 4°C |
| DEC 12 | 5°C | 5°C | 4°C | 4°C |
| DEC 13 | 5°C | 5°C | 4°C | 4°C |
| DEC 14 | 5°C | 5°C | 4°C | 4°C |
| DEC 15 | 5°C | 5°C | 4°C | 4°C |
| DEC 16 | 4°C | 5°C | 4°C | 4°C |
| DEC 17 | 4°C | 4°C | 3°C | 3°C |
| DEC 18 | 4°C | 5°C | 3°C | 3°C |
| DEC 19 | 3°C | 4°C | 3°C | 2°C |
| DEC 20 | 4°C | 4°C | 3°C | 3°C |
| DEC 21 | 3°C | 5°C | 3°C | 2°C |
| DEC 22 | 3°C | 5°C | 3°C | 2°C |
| DEC 23 | 3°C | 4°C | 3°C | 3°C |
| DEC 24 | 4°C | 5°C | 2°C | 3°C |
| DEC 25 | 4°C | 5°C | 3°C | 3°C |
| DEC 26 | 4°C | 5°C | 3°C | 3°C |
| DEC 27 | 3°C | 5°C | 2°C | 3°C |
| DEC 28 | 4°C | 5°C | 3°C | 3°C |
| DEC 29 | 3°C | 4°C | 3°C | 2°C |
| DEC 30 | 4°C | 5°C | 3°C | 2°C |
| DEC 31 | 4°C | 5°C | 3°C | 2°C |
December: Climate and Swimming Opportunities
Average Night Air Temperature
-5°C
Average Day Air Temperature
-2°C
Precipitation Amount per Month
62 mm
Number of Rainy Days
13
Daylight per Day
6 hrs
Sunshine per Day
1 hrs
Average Wind Speed
18 km/h
Average Humidity
89%
At such water and air temperatures, swimming is extremely harsh and generally not enjoyable. The risk of rapid chilling is high, so most people avoid entering the water.