01.09
tue
tue
Day
84°F
SW 4 mph
Precip.
2%
2%
Night
70°F
W 6 mph
Precip.
4%
4%
02.09
wed
wed
Day
84°F
SW 3 mph
Precip.
1%
1%
Night
70°F
W 6 mph
Precip.
4%
4%
03.09
thu
thu
Day
86°F
SW 6 mph
Precip.
1%
1%
Night
70°F
W 4 mph
Precip.
3%
3%
04.09
fri
fri
Day
86°F
E 4 mph
Precip.
1%
1%
Night
70°F
W 3 mph
Precip.
3%
3%
05.09
sat
sat
Day
88°F
E 5 mph
Precip.
1%
1%
Night
72°F
W 4 mph
Precip.
3%
3%
06.09
sun
sun
Day
84°F
SW 8 mph
Precip.
1%
1%
Night
68°F
W 6 mph
Precip.
4%
4%
07.09
mon
mon
Day
84°F
NW 3 mph
Precip.
1%
1%
Night
72°F
W 4 mph
Precip.
13%
13%
Sea water temperature in September, °F
Show year:
2025
2024
2023
The average sea water temperature in September of 2025 was 75.2°F. The highest and lowest sea temperatures during the month were 77.5°F and 73.0°F.
Air temperature in Koper, °F
Precipitation total in Koper, in.
* Charts above show average data for the last 3 years.
Best time for vacation in Koper
Koper on a weather map
Places in Slovenia:
Name
°F
24 Hours Forecast
Koper
Local time: 10:38
September 01, tuesday
1200
84°F
SW
4 mph
4 mph
1500
88°F
S
4 mph
4 mph
1800
82°F
S
5 mph
5 mph
2100
72°F
W
4 mph
4 mph
September 02, wednesday
0000
70°F
W
6 mph
6 mph
0300
68°F
W
6 mph
6 mph
0600
66°F
W
6 mph
6 mph
0900
73°F
W
5 mph
5 mph
