Swimming in Slovenia in september 2025 Sea temperature by city in september
Do you want to go to the beach in Slovenia in september 2025? Is it the right month to go for pleasant temperatures and staying in the water for a long time? The answer is on this page with the sea temperatures in september in Slovenia by city and our opinion on the chances of enjoying pleasant sea conditions.
Sea temperature in Slovenia in september 2025
Here, find the average sea temperature in Slovenia in september in several coastal cities.
74°F
min: 69°F / max: 80°F
Ankaran
74°F
min: 69°F / max: 80°F
74°F
min: 69°F / max: 80°F
Koper
74°F
min: 69°F / max: 80°F
Portorož
74°F
min: 69°F / max: 80°F
Where should you go swimming in Slovenia in the month of september?
Swimming in Slovenia in september is pleasant
In september in Slovenia swimming conditions are generally the same everywhere.
As for Piran, Ankaran, Izola, Koper and Portorož, swimming is pleasant in september. The sea water is 74°F on average (min: 69°F/max: 80°F) so you can easily spend time in the water.
Where to go swimming in Slovenia in september: the map of sea temperatures
ideal swimming 
pleasant swimming 
cool swimming 
cold swimming 
freezing swimmingWater temperature and seasonal norms in september
Piran
| September | |||
| Average sea temperature | 74°F | ||
| Minimum sea temperature | 69°F | ||
| Maximum sea temperature | 80°F | ||
| Average outside temperature | 70°F | ||
| Maximum outside temperature | 76°F | ||
| Minimum outside temperature | 63°F | ||
| Precipitation | 9.4in | ||
| Number of days of precipitation | 9 jour(s) (31%) | ||
| Cloud cover | 27% | ||
| Our opinion | pleasant swimming |
More information on swimming in Piran in september
Ankaran
| September | |||
| Average sea temperature | 74°F | ||
| Minimum sea temperature | 69°F | ||
| Maximum sea temperature | 80°F | ||
| Average outside temperature | 70°F | ||
| Maximum outside temperature | 76°F | ||
| Minimum outside temperature | 63°F | ||
| Precipitation | 9.4in | ||
| Number of days of precipitation | 9 jour(s) (31%) | ||
| Cloud cover | 27% | ||
| Our opinion | pleasant swimming |
Izola
| September | |||
| Average sea temperature | 74°F | ||
| Minimum sea temperature | 69°F | ||
| Maximum sea temperature | 80°F | ||
| Average outside temperature | 70°F | ||
| Maximum outside temperature | 76°F | ||
| Minimum outside temperature | 63°F | ||
| Precipitation | 9.4in | ||
| Number of days of precipitation | 9 jour(s) (31%) | ||
| Cloud cover | 27% | ||
| Our opinion | pleasant swimming |
More information on swimming in Izola in september
Koper
| September | |||
| Average sea temperature | 74°F | ||
| Minimum sea temperature | 69°F | ||
| Maximum sea temperature | 80°F | ||
| Average outside temperature | 70°F | ||
| Maximum outside temperature | 76°F | ||
| Minimum outside temperature | 63°F | ||
| Precipitation | 9.4in | ||
| Number of days of precipitation | 9 jour(s) (31%) | ||
| Cloud cover | 27% | ||
| Our opinion | pleasant swimming |
Portorož
| September | |||
| Average sea temperature | 74°F | ||
| Minimum sea temperature | 69°F | ||
| Maximum sea temperature | 80°F | ||
| Average outside temperature | 70°F | ||
| Maximum outside temperature | 76°F | ||
| Minimum outside temperature | 63°F | ||
| Precipitation | 9.4in | ||
| Number of days of precipitation | 9 jour(s) (31%) | ||
| Cloud cover | 27% | ||
| Our opinion | pleasant swimming |
List of coastal cities in Slovenia
| Piran in september | pleasant swimming |
| Ankaran in september | pleasant swimming |
| Izola in september | pleasant swimming |
| Koper in september | pleasant swimming |
| Portorož in september | pleasant swimming |