Koper
September
Weather in Koper for September 2026
Your guide to Koper weather in September - trends and predictions
Giallo Pioggia Allerta - See hour by hour.
So far, September 2026 in Koper is slightly warmer than the historical average by 1.4 °C.
The forecast for the next days in Koper predicts temperatures to be around 27 °C, close to the historical average.
In general, the average temperature in Koper at the beginning of September is 29.1 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 22.3 °C by the end of September.
Koper in September brings notable rainfall, with an average of 18 rainy days and a total precipitation of 156.7 mm.
Official Weather Alert ⚠️
Temperatures
Rain 🌧️
12
Dry days
18
Rainy days
0
Snow days
23°/14°
Temperatures
12 km/h
Avg max wind
72 %
Avg humidity
Koper Weather September
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Temperatures trend during September in Koper
See the weather trend as well as the moving average line
September weather in Koper day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| 1 Sept. |  Partly cloudy | 30° /19° | 0.1 mm | 7 | |
| 2 Sept. |  Sunny | 29° /18° | 3.7 mm | 7 | |
| 3 Sept. |  Patchy rain possible | 29° /18° | 0.7 mm | 6 | |
| 4 Sept. | Sunny | 30° /18° | 0.1 mm | 6 | |
| 5 Sept. | Patchy rain possible | 30° /19° | 2.6 mm | 7 | |
| 6 Sept. |  Patchy light rain with thunder | 28° /17° | 2.5 mm | 6 | |
| 7 Sept. | Sunny | 28° /16° | 0 mm | 6 | |
| 8 Sept. | Light rain shower | 28° /17° | 2.7 mm | 6 | |
| 9 Sept. | Light rain shower | 25° /16° | 14.5 mm | 4 | |
| 10 Sept. |  Moderate or heavy rain shower | 23° /15° | 40.5 mm | 4 | |
| 11 Sept. | Partly cloudy | 23° /15° | 20.3 mm | 4 | |
| 12 Sept. | Moderate or heavy rain shower | 22° /12° | 27.8 mm | 5 | |
| 13 Sept. | Sunny | 25° /14° | 0 mm | 5.2 | |
| 14 Sept. |  Overcast | 26° /16° | 0 mm | 5.1 | |
| 15 Sept. | Sunny | 27° /16° | 0 mm | 7 | |
| 16 Sept. | Sunny | 26° /17° | 0 mm | 7 | |
| 17 Sept. | Partly cloudy | 25° /16° | 6.9 mm | 7 | |
| 18 Sept. | Patchy rain possible | 27° /17° | 4 mm | 6 | |
| 19 Sept. | Overcast | 26° /18° | 1 mm | 6 | |
| 20 Sept. | Overcast | 28° /18° | 0 mm | 6 | |
| 21 Sept. | Patchy rain possible | 28° /18° | 0.7 mm | 6 | |
| 22 Sept. | Overcast | 27° /18° | 0 mm | 6 | |
| 23 Sept. | Patchy rain possible | 28° /18° | 0.1 mm | 6 | |
| 24 Sept. | Sunny | 28° /17° | 0 mm | 7 | |
| 25 Sept. | Sunny | 28° /17° | 0 mm | 7 | |
| 26 Sept. | Light rain shower | 20° /13° | 1.1 mm | 5 | |
| 27 Sept. | Light rain shower | 22° /14° | 4.6 mm | 5 | |
| 28 Sept. | Patchy rain possible | 21° /11° | 1.5 mm | 5 | |
| 29 Sept. | Patchy rain possible | 20° /10° | 0.4 mm | 5 | |
| 30 Sept. | Partly cloudy | 17° /9° | 0.3 mm | 5 | |
| Next | |||||
Important Notice
Our weather forecast for Koper in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Koper forecast closer to your planned date for the most up-to-date weather information.
Change Month
Koper in September - FAQ
What are the expected maximum and minimum temperatures in Koper during September?
Enjoy moderate daytime temperatures of up to 23° and cooler nights around 14°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Koper during September?
Significant rainfall exceeding 156.7 mm is expected in Koper during September, occurring over more than 18 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Koper during September?
The average wind speed in Koper during September is 12 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Koper
Explore the daily rainfall trends and prepare for Kopers September weather 💧
Typically, Koper has 18 rainy days in September with a total of 156.7 mm of rainfall.
UV exposure in Koper during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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