Water temperature in Grand Marais (MN) in December
Is it warm enough to swim in Grand Marais in December? Average water temperature in Grand Marais in December is 39.4°F and therefore is not suitable for comfortable swimming. The warmest water in Grand Marais in December is 43.2°F, and the coldest is 32.5°F. To find out the sea temperature today and in the coming days, go to Current sea temperature in Grand Marais
Changes water temperature in Grand Marais in December 2025, 2024
To get an accurate forecast for the water temperature in Grand Marais for any chosen month, compare two years within a 10 year range using the chart below. In addition to the sea water temperature in Grand Marais, the selected years in the table also show the values of the maximum and minimum temperatures on each of the days of December.
You can choose any other years:
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| December 1 | 40.3°F | 42.4°F | 38.7°F | 42.4°F |
| December 2 | 40.3°F | 43.2°F | 38.8°F | 43.2°F |
| December 3 | 39.6°F | 43°F | 37.9°F | 43°F |
| December 4 | 39.2°F | 42.8°F | 38.3°F | 42.8°F |
| December 5 | 39.4°F | 42.4°F | 38.7°F | 42.6°F |
| December 6 | 39°F | 42.1°F | 37.2°F | 42.1°F |
| December 7 | 39°F | 41.7°F | 37.2°F | 41.7°F |
| December 8 | 38.5°F | 41.4°F | 37.4°F | 41.4°F |
| December 9 | 38.3°F | 41°F | 38.3°F | 41.4°F |
| December 10 | 39.2°F | 40.5°F | 38.5°F | 41.2°F |
| December 11 | 38.8°F | 40.1°F | 38.3°F | 41°F |
| December 12 | 38.7°F | 40.3°F | 38.1°F | 40.8°F |
| December 13 | 38.3°F | 40.1°F | 37.8°F | 41°F |
| December 14 | 38.1°F | 41°F | 37.4°F | 41°F |
| December 15 | 38.3°F | 40.6°F | 36.3°F | 40.6°F |
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| December 16 | 39.2°F | 40.5°F | 36.7°F | 40.5°F |
| December 17 | 38.7°F | 40.3°F | 37°F | 40.3°F |
| December 18 | 38.7°F | 40.3°F | 36.7°F | 40.5°F |
| December 19 | 37.9°F | 40.1°F | 37°F | 40.3°F |
| December 20 | 39.4°F | 39.9°F | 36.9°F | 40.6°F |
| December 21 | 38.3°F | 40.1°F | 36.7°F | 40.5°F |
| December 22 | 37°F | 39.7°F | 37°F | 39.9°F |
| December 23 | 38.7°F | 39.9°F | 37.4°F | 40.1°F |
| December 24 | 38.3°F | 39.4°F | 37.4°F | 40.3°F |
| December 25 | 37.6°F | 39°F | 36.3°F | 39.9°F |
| December 26 | 37.4°F | 38.7°F | 35.2°F | 39.2°F |
| December 27 | 37°F | 38.3°F | 35.4°F | 40.1°F |
| December 28 | 37.2°F | 38.8°F | 35.6°F | 39.9°F |
| December 29 | 37.9°F | 40.1°F | 35.1°F | 40.1°F |
| December 30 | 36.9°F | 39.7°F | 34.5°F | 41.5°F |
| December 31 | 37.4°F | 39.4°F | 32.5°F | 39.4°F |
Average water temperature in Grand Marais in December over a decade
| 2016 | 2017 | 2018 | 2019 | 2020 |
| 40.3°F | 39°F | 39.4°F | 38.8°F | 39.6°F |
| 2021 | 2022 | 2023 | 2024 | 2025 |
| 40.3°F | 39.2°F | 39.2°F | 40.5°F | 40.1°F |
Grand Marais sea state in December
Chart comparing the height of waves in Grand Marais in December over the past years. The red line indicates the height of the waves when swimming in the sea is prohibited. To view the current sea conditions, click on the graph.
Grand Marais water temperature during other months:
You can also view information about water temperature for other months by clicking on the month button below
