Water temperature in Monroe Harbor (IL) in May
Is it warm enough to swim in Monroe Harbor in May? Average water temperature in Monroe Harbor in May is 51.4°F and therefore is not suitable for comfortable swimming. The warmest water in Monroe Harbor in May is 65.5°F, and the coldest is 43.3°F. To find out the sea temperature today and in the coming days, go to Current sea temperature in Monroe Harbor
Changes water temperature in Monroe Harbor in May 2025, 2024
To get an accurate forecast for the water temperature in Monroe Harbor for any chosen month, compare two years within a 10 year range using the chart below. In addition to the sea water temperature in Monroe Harbor, the selected years in the table also show the values of the maximum and minimum temperatures on each of the days of May.
You can choose any other years:
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| May 1 | 49.8°F | 46°F | 43.3°F | 49.8°F |
| May 2 | 49.3°F | 47.1°F | 44.1°F | 49.5°F |
| May 3 | 50.4°F | 49.3°F | 44.4°F | 50.4°F |
| May 4 | 50.2°F | 50°F | 44.4°F | 50.2°F |
| May 5 | 50.2°F | 51.1°F | 45°F | 51.1°F |
| May 6 | 49.6°F | 51.4°F | 44.2°F | 51.4°F |
| May 7 | 48.6°F | 52.5°F | 45.7°F | 52.5°F |
| May 8 | 49.6°F | 52.2°F | 46.2°F | 52.2°F |
| May 9 | 51.1°F | 52.3°F | 46.6°F | 52.3°F |
| May 10 | 50.5°F | 54.7°F | 45.7°F | 54.7°F |
| May 11 | 51.4°F | 55.8°F | 44.4°F | 55.8°F |
| May 12 | 50.5°F | 55.8°F | 45.9°F | 55.8°F |
| May 13 | 49.3°F | 56.5°F | 46.4°F | 56.5°F |
| May 14 | 49.5°F | 56.3°F | 47.1°F | 56.3°F |
| May 15 | 49.6°F | 57°F | 47.5°F | 57°F |
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| May 16 | 52.5°F | 55.6°F | 47.7°F | 55.6°F |
| May 17 | 52.5°F | 56.8°F | 48°F | 56.8°F |
| May 18 | 54°F | 58.3°F | 45.9°F | 58.3°F |
| May 19 | 55.2°F | 60.6°F | 46.8°F | 60.6°F |
| May 20 | 54.9°F | 59.7°F | 45.9°F | 59.7°F |
| May 21 | 54.9°F | 60.4°F | 45.7°F | 60.4°F |
| May 22 | 52.2°F | 60.3°F | 46.4°F | 60.3°F |
| May 23 | 52.7°F | 60.1°F | 47.7°F | 60.1°F |
| May 24 | 53.1°F | 59.9°F | 48.6°F | 59.9°F |
| May 25 | 55°F | 59.7°F | 48.9°F | 60.8°F |
| May 26 | 55.6°F | 59°F | 50.4°F | 62.6°F |
| May 27 | 54.7°F | 58.8°F | 50.5°F | 63.3°F |
| May 28 | 54°F | 60.8°F | 50.7°F | 64.9°F |
| May 29 | 53.6°F | 59.7°F | 50.9°F | 65.5°F |
| May 30 | 55°F | 59.2°F | 51.6°F | 64.8°F |
| May 31 | 55.4°F | 59.5°F | 53.6°F | 65.5°F |
Average water temperature in Monroe Harbor in May over a decade
| 2016 | 2017 | 2018 | 2019 | 2020 |
| 50.2°F | 50.4°F | 52.9°F | 49.3°F | 47.5°F |
| 2021 | 2022 | 2023 | 2024 | 2025 |
| 52.7°F | 51.6°F | 50.9°F | 55.9°F | 52.2°F |
Monroe Harbor sea state in May
Chart comparing the height of waves in Monroe Harbor in May 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.
Monroe Harbor water temperature during other months:
You can also view information about water temperature for other months by clicking on the month button below
