Current Sea Water Temperature:
+56.4°F
| Maximum Sea Water Temperature in December: | 61.2°F |
| Minimum Sea Water Temperature in December: | 50.2°F |
| Average water temperature in December: | 55.7°F |
| detailed information | |
Sea Water Temperature for the Last 10 Days:
| December 13 | 56.4°F | December 08 | 57.6°F |
| December 12 | 55.8°F | December 07 | 57.0°F |
| December 11 | 56.2°F | December 06 | 57.2°F |
| December 10 | 56.8°F | December 05 | 57.0°F |
| December 09 | 57.4°F | December 04 | 57.0°F |
When is the Warmest Sea for Koper?
According to our data for the last three years for Koper the highest average sea water temperature was in August, July and September.
Average Water Temperature by Month, °F
Sea Water Temperature in August
The average sea surface temperature in August 2025 for Koper was 79.6°F. The maximum and minimum values were 76.8°F and 82.4°F respectively.
Sea Water Temperature in July
The average sea surface temperature in July 2025 for Koper was 81.9°F. The maximum and minimum values were 79.4°F and 85.4°F respectively.
Sea Water Temperature in September
The average sea surface temperature in September 2025 for Koper was 78.0°F. The maximum and minimum values were 75.6°F and 80.6°F respectively.
Slovenia Resorts:
NAME
F°
| Bohinjsko Jezero |  |
+36 |
| Cerkno | |
+42 |
| Dolenjske Toplice | |
+30 |
| Isola | |
+42 |
| Koper | |
+42 |
| Kranjska Gora | |
+36 |
| Ljubljana | |
+36 |
| Maribor |  |
+34 |
| Moravske Toplice | |
+36 |
| Piran | |
+42 |
| Portoroz | |
+42 |
| Rogaska Slatina | |
+36 |
| Strunjan | |
+42 |
| Terme Radenci | |
+34 |
| Zrece | |
+36 |
Countries:
NAME
POPULARITY
24 Hours Weather Forecast
Koper
Local time: 23:24
14 dec, sunday
| 0000 |  |
42°F | W 4 mph |
| 0300 | |
42°F | W 4 mph |
| 0600 | |
42°F | W 4 mph |
| 0900 |  |
44°F | W 4 mph |
| 1200 | |
54°F | SW 1 mph |
| 1500 | |
52°F | SE 1 mph |
| 1800 | |
46°F | W 2 mph |
| 2100 | |
38°F | W 4 mph |