Water temperature in Marathon Key (FL) in October
Is it warm enough to swim in Marathon Key in October? Average water temperature in Marathon Key in October is 82.9°F and therefore suitable for comfortable swimming. The warmest sea in Marathon Key in October is 87.1°F, and the coldest is 78.4°F. To find out the sea temperature today and in the coming days, go to Current sea temperature in Marathon Key
Changes water temperature in Marathon Key in October 2025, 2024
To get an accurate forecast for the water temperature in Marathon Key for any chosen month, compare two years within a 10 year range using the chart below. In addition to the sea water temperature in Marathon Key, the selected years in the table also show the values of the maximum and minimum temperatures on each of the days of October.
You can choose any other years:
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| October 1 | 86°F | 86.2°F | 82.9°F | 86.2°F |
| October 2 | 85.5°F | 86.5°F | 82.8°F | 86.5°F |
| October 3 | 85.8°F | 87.1°F | 82.9°F | 87.1°F |
| October 4 | 85.3°F | 86.4°F | 82.4°F | 86.4°F |
| October 5 | 85.1°F | 86.5°F | 82.4°F | 86.5°F |
| October 6 | 84.7°F | 86°F | 82°F | 86°F |
| October 7 | 85.3°F | 85.5°F | 81.9°F | 85.8°F |
| October 8 | 85.5°F | 84.9°F | 81.7°F | 85.6°F |
| October 9 | 85.5°F | 84.6°F | 81.3°F | 85.6°F |
| October 10 | 85.1°F | 83.7°F | 81.5°F | 85.8°F |
| October 11 | 84.4°F | 83.8°F | 82°F | 86°F |
| October 12 | 84.6°F | 83.7°F | 81.9°F | 85.5°F |
| October 13 | 84.4°F | 83.5°F | 81.9°F | 86.4°F |
| October 14 | 84.2°F | 83.1°F | 81.7°F | 86°F |
| October 15 | 83.7°F | 83.5°F | 81.3°F | 85.3°F |
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| October 16 | 83.5°F | 83.1°F | 81.3°F | 85.5°F |
| October 17 | 83.1°F | 82.6°F | 81.3°F | 84.9°F |
| October 18 | 82.6°F | 82.4°F | 81.3°F | 84.6°F |
| October 19 | 82.2°F | 81.1°F | 84°F | |
| October 20 | 81.5°F | 80.6°F | 84.6°F | |
| October 21 | 81.1°F | 79.7°F | 84.2°F | |
| October 22 | 80.8°F | 79.7°F | 84.4°F | |
| October 23 | 80.8°F | 80.1°F | 84.6°F | |
| October 24 | 81.1°F | 80.1°F | 84.7°F | |
| October 25 | 82°F | 79.5°F | 84.4°F | |
| October 26 | 82.2°F | 79.3°F | 84°F | |
| October 27 | 82.6°F | 79.2°F | 83.8°F | |
| October 28 | 82.4°F | 79.5°F | 84°F | |
| October 29 | 81.1°F | 79.2°F | 84.2°F | |
| October 30 | 80.8°F | 78.6°F | 83.8°F | |
| October 31 | 81.1°F | 78.4°F | 84.6°F |
Average water temperature in Marathon Key in October over a decade
| 2015 | 2016 | 2017 | 2018 | 2019 |
| 82.6°F | 82.6°F | 83.1°F | 83.1°F | 83.8°F |
| 2020 | 2021 | 2022 | 2023 | 2024 |
| 83.8°F | 84°F | 82.2°F | 83.7°F | 83.3°F |
Marathon Key sea state in October
Chart comparing the height of waves in Marathon Key in October 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.
Marathon Key water temperature during other months:
You can also view information about water temperature for other months by clicking on the month button below
