Koper
September
Weather in Koper for September 2025
Your guide to Koper weather in September - trends and predictions
Moderate Thunderstorm Risk Warning - See hour by hour.
Until now, September 2025 in Koper is slightly cooler than the historical average by -0.8 °C.
Expect cooler weather in the next days in Koper with the forecast suggesting a temperature of 22 °C, lower than the historical average.
In general, the average temperature in Koper at the beginning of September is 28 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 17.9 °C by the end of September.
The climate of Koper in September is notably wet, with an average of 13 rainy days, and a total of 157.8 mm of precipitation.
Official Weather Alert ⚠️
Temperatures
Rain 🌧️
17
Dry days
13
Rainy days
0
Snow days
23°/14°
Temperatures
15 km/h
Avg max wind
70 %
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° | 0.2 mm | 8 | |
| 2 Sept. |  Sunny | 28° /19° | 5.6 mm | 7 | |
| 3 Sept. |  Patchy rain possible | 28° /18° | 1 mm | 6 | |
| 4 Sept. | Patchy rain possible | 29° /18° | 0.2 mm | 7 | |
| 5 Sept. | Patchy rain possible | 29° /18° | 3.9 mm | 7 | |
| 6 Sept. |  Patchy light rain with thunder | 26° /17° | 3.8 mm | 6 | |
| 7 Sept. | Sunny | 26° /16° | 0 mm | 7 | |
| 8 Sept. | Light rain shower | 26° /16° | 4.1 mm | 6 | |
| 9 Sept. | Light rain shower | 23° /16° | 14.5 mm | 5 | |
| 10 Sept. | Patchy rain possible | 23° /16° | 26.1 mm | 6 | |
| 11 Sept. | Partly cloudy | 24° /15° | 8.1 mm | 6 | |
| 12 Sept. |  Moderate or heavy rain shower | 22° /12° | 27.8 mm | 5 | |
| 13 Sept. | Patchy rain possible | 21° /12° | 0.5 mm | 5 | |
| 14 Sept. |  Patchy light drizzle | 19° /11° | 8 mm | 5 | |
| 15 Sept. | Patchy rain possible | 18° /11° | 0 mm | 4 | |
| 16 Sept. |  Moderate rain | 24° /14° | 12.5 mm | 1.1 | |
| 17 Sept. | Patchy rain possible | 24° /13° | 0.2 mm | 1.3 | |
| 18 Sept. | Sunny | 25° /12° | 0 mm | 1.4 | |
| 19 Sept. | Sunny | 28° /16° | 0 mm | 1.4 | |
| 20 Sept. | Sunny | 28° /18° | 0 mm | 1.6 | |
| 21 Sept. | Sunny | 26° /18° | 0 mm | 6 | |
| 22 Sept. | Sunny | 27° /18° | 0 mm | 6 | |
| 23 Sept. | Patchy rain possible | 19° /17° | 4.2 mm | 4 | |
| 24 Sept. | Moderate rain | 19° /9° | 6.4 mm | 3 | |
| 25 Sept. | Patchy rain possible | 18° /10° | 1.1 mm | 3 | |
| 26 Sept. | Patchy rain possible | 17° /11° | 1.1 mm | 3 | |
| 27 Sept. | Patchy rain possible | 19° /11° | 3 mm | 3 | |
| 28 Sept. | Patchy rain possible | 16° /14° | 3.5 mm | 3 | |
| 29 Sept. | Partly cloudy | 18° /13° | 0 mm | 5 | |
| 30 Sept. | Partly cloudy | 18° /8° | 0 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.
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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 157.8 mm is expected in Koper during September, occurring over more than 13 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 15 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 💧
UV exposure in Koper during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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