France · Loire-Atlantique
Sea temperature at Portmain
Pleasant for swimming
Updated hourly from the live marine forecast. See the 12-month typical range and, where available, real measured readings further down the page.
7-day outlook
7-day sea temperature forecast from Open-Meteo, refreshed hourly.
Sea temperature
Next 7 days, °C
View as table
| Day | Sea temp (°C) |
|---|---|
| Wed 2 | 21.7 |
| Thu 3 | 21.8 |
| Fri 4 | 22.0 |
| Sat 5 | 22.8 |
| Sun 6 | 22.5 |
| Mon 7 | 22.6 |
| Tue 8 | 22.4 |
Sea temperature by month
Modeled climatology derived from latitude and season.
Typical vs. measured sea temperature
12-month view, °C — modeled line vs. measured sample averages
View as table
| Month | Modeled (°C) | Measured avg. (°C) |
|---|---|---|
| Jan | 15 | — |
| Feb | 14 | — |
| Mar | 15 | — |
| Apr | 17 | — |
| May | 19 | — |
| Jun | 22 | — |
| Jul | 23 | — |
| Aug | 24 | — |
| Sep | 24 | — |
| Oct | 22 | — |
| Nov | 20 | — |
| Dec | 17 | — |
No measured in-season sea temperature has been published for Portmain yet — the chart above shows the modeled climatology only. Some countries (Croatia, via IZOR) also record the sea temperature at each official water sample; check the water quality page for this beach's sampling status.
Frequently asked questions
What's the current water temperature at Portmain?
As of the latest hourly update, the sea at Portmain is around 21°C. See the 7-day chart above for how it's trending, and the monthly chart further down for what's typical this time of year. That's the reading right off Loire-Atlantique.
When does Portmain have the warmest water?
The modeled climatology puts the comfortably-warm window (above 22°C) at July–September, with August typically the warmest point in that stretch. That applies to the water around Loire-Atlantique.
Is the sea temperature chart above measured or estimated?
For Portmain, the chart above shows a modeled estimate only, derived from latitude and season — no measured average yet. Some countries, Croatia's IZOR among them, also record the sea temperature at each official sample, plotted alongside the model where available.