Water temperature in Portsmouth (RI) in March
Is it warm enough to swim in Portsmouth in March? Average water temperature in Portsmouth in March is 40.3°F and therefore is not suitable for comfortable swimming. The warmest sea in Portsmouth in March is 50.4°F, and the coldest is 33.6°F. To find out the sea temperature today and in the coming days, go to Current sea temperature in Portsmouth
Changes water temperature in Portsmouth in March 2026, 2025
To get an accurate forecast for the water temperature in Portsmouth for any chosen month, compare two years within a 10 year range using the chart below. In addition to the sea water temperature in Portsmouth, the selected years in the table also show the values of the maximum and minimum temperatures on each of the days of March.
You can choose any other years:
| Day | 2026 | 2025 | Min | Max |
|---|---|---|---|---|
| March 1 | 35.1°F | 39.9°F | 33.6°F | 43.7°F |
| March 2 | 35.2°F | 38.3°F | 33.6°F | 43.7°F |
| March 3 | 35.2°F | 38.3°F | 34°F | 43.9°F |
| March 4 | 36.7°F | 38.1°F | 34°F | 43.9°F |
| March 5 | 33.8°F | 38.7°F | 33.8°F | 42.6°F |
| March 6 | 34.7°F | 40.8°F | 34.2°F | 42.6°F |
| March 7 | 36°F | 39°F | 34.2°F | 42.6°F |
| March 8 | 36.5°F | 39°F | 34.2°F | 44.2°F |
| March 9 | 37.8°F | 38.7°F | 34.2°F | 45°F |
| March 10 | 39.4°F | 34.7°F | 44.6°F | |
| March 11 | 40.8°F | 35.6°F | 44.6°F | |
| March 12 | 41°F | 35.2°F | 45°F | |
| March 13 | 41.7°F | 35.2°F | 45.5°F | |
| March 14 | 43.5°F | 35.4°F | 45.7°F | |
| March 15 | 43.7°F | 35.6°F | 45.3°F |
| Day | 2026 | 2025 | Min | Max |
|---|---|---|---|---|
| March 16 | 44.2°F | 35.4°F | 45.3°F | |
| March 17 | 44.6°F | 35.2°F | 45.9°F | |
| March 18 | 44.4°F | 35.4°F | 46.8°F | |
| March 19 | 42.6°F | 35.6°F | 47.1°F | |
| March 20 | 43.2°F | 35.8°F | 47.3°F | |
| March 21 | 43°F | 35.6°F | 47.8°F | |
| March 22 | 43.3°F | 35.2°F | 49.1°F | |
| March 23 | 43°F | 35.4°F | 50.4°F | |
| March 24 | 44.1°F | 35.6°F | 49.1°F | |
| March 25 | 43.2°F | 36.1°F | 50°F | |
| March 26 | 42.8°F | 36.9°F | 49.3°F | |
| March 27 | 43.5°F | 37.2°F | 48.4°F | |
| March 28 | 43°F | 37.2°F | 48°F | |
| March 29 | 43°F | 36.7°F | 48.2°F | |
| March 30 | 42.8°F | 36.9°F | 48.6°F | |
| March 31 | 44.4°F | 37.2°F | 47.8°F |
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Average water temperature in Portsmouth in March over a decade
| 2016 | 2017 | 2018 | 2019 | 2020 |
| 41°F | 39.4°F | 40.5°F | 39.7°F | 42.8°F |
| 2021 | 2022 | 2023 | 2024 | 2025 |
| 39.7°F | 41.9°F | 41.5°F | 42.4°F | 41.7°F |
Portsmouth sea state in March
Chart comparing the height of waves in Portsmouth in March 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.
Portsmouth water temperature during other months:
You can also view information about water temperature for other months by clicking on the month button below
