Mariehamn — Water Temperature in May
Water Temperature Range
-1°C
minimum
6°C
average
10°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 | 2026 | 2025 | 2024 | 2023 |
|---|---|---|---|---|
| MAY 1 | -10°C | 3°C | 5°C | 5°C |
| MAY 2 | 5°C | 4°C | 5°C | 5°C |
| MAY 3 | 5°C | 4°C | 5°C | 6°C |
| MAY 4 | 6°C | 4°C | 5°C | 5°C |
| MAY 5 | 5°C | 4°C | 5°C | 6°C |
| MAY 6 | 6°C | 4°C | 5°C | 5°C |
| MAY 7 | 6°C | 4°C | 5°C | 5°C |
| MAY 8 | 5°C | 4°C | 4°C | 5°C |
| MAY 9 | 6°C | 4°C | 5°C | 5°C |
| MAY 10 | 6°C | 4°C | 5°C | 4°C |
| MAY 11 | 7°C | 5°C | 5°C | 6°C |
| MAY 12 | 7°C | 5°C | 5°C | 6°C |
| MAY 13 | 7°C | 5°C | 5°C | 6°C |
| MAY 14 | 7°C | 6°C | 6°C | 7°C |
| MAY 15 | 7°C | 6°C | 6°C | 7°C |
| MAY 16 | 7°C | 5°C | 5°C | 7°C |
| MAY 17 | 7°C | 6°C | 6°C | 7°C |
| MAY 18 | 7°C | 6°C | 6°C | 7°C |
| MAY 19 | 7°C | 5°C | 5°C | 6°C |
| MAY 20 | 8°C | 6°C | 6°C | 7°C |
| MAY 21 | 8°C | 6°C | 6°C | 7°C |
| MAY 22 | 9°C | 7°C | 6°C | 8°C |
| MAY 23 | 9°C | 7°C | 6°C | 8°C |
| MAY 24 | 9°C | 7°C | 6°C | 9°C |
| MAY 25 | 9°C | 7°C | 7°C | 8°C |
| MAY 26 | 9°C | 8°C | 7°C | 9°C |
| MAY 27 | 9°C | 7°C | 7°C | 7°C |
| MAY 28 | 9°C | 7°C | 8°C | 7°C |
| MAY 29 | 9°C | 8°C | 8°C | 7°C |
| MAY 30 | 9°C | 8°C | 7°C | 8°C |
| MAY 31 | 9°C | 9°C | 8°C | 9°C |
May: Climate and Swimming Opportunities
Average Night Air Temperature
5°C
Average Day Air Temperature
15°C
Precipitation Amount per Month
36 mm
Number of Rainy Days
8
Daylight per Day
17 hrs
Sunshine per Day
8 hrs
Average Wind Speed
15 km/h
Average Humidity
69%
At such water and air temperatures, swimming feels icy and can be a shock to the body. If you go in at all, keep it extremely short and warm up immediately afterward.