Average temperature in September is 20.4 °C
Average daytime temperature is 26.8 °C
Average night temperature is 14.5 °C
Absolute maximum temperature: 31.1 °C
Absolute minimum temperature: 10.7 °C
Number of sunny days: 21
Number of rainy days: 9
Number of snow days:
Precipitation sum: 46 mm
* Weather data for Siena Italy is based on climate observations for 2023 year
| September (°C) | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Maximum temperature | 25.5 | 28.4 | 30.5 | 27.8 | 26 | 27.9 | 29.8 | 31.1 | 30.8 | 30.8 | 31 | 29.7 | 27.3 | 25.9 | 26.3 | 26.1 | 27.7 | 28.3 | 28.1 | 24.5 | 24 | 23.3 | 20.9 | 20.4 | 21.9 | 24.7 | 25.9 | 26.5 | 26 | 26.8 |
| Apparent max temperature | 25.3 | 29.1 | 31.7 | 26.5 | 23.5 | 26.5 | 29.8 | 31 | 31.4 | 30.7 | 31.6 | 30 | 28.6 | 27.5 | 28.7 | 27.5 | 29.2 | 30.4 | 27.4 | 25.7 | 24.8 | 22.1 | 19.8 | 18.4 | 20.6 | 25.5 | 27 | 26.9 | 26.7 | 26.4 |
| Mean temperature | 20 | 21.5 | 23.6 | 22.6 | 20.5 | 20.8 | 21.6 | 22.5 | 22.7 | 22.8 | 23.3 | 22.9 | 21.3 | 20.8 | 20.8 | 21.2 | 22.3 | 21.7 | 21.6 | 19.6 | 19.1 | 19.2 | 17.2 | 15.8 | 16.5 | 17.1 | 17.9 | 18.4 | 18.4 | 18.8 |
| Apparent mean temperature | 16 | 13.7 | 17.8 | 17.4 | 14.5 | 13.4 | 13.9 | 14.5 | 13.8 | 13.6 | 15.5 | 15.7 | 16 | 17.5 | 18.2 | 17.1 | 18 | 17.5 | 17 | 14.9 | 16.9 | 16.5 | 12.1 | 9.6 | 9.9 | 10.6 | 10.5 | 11.2 | 11.2 | 11.4 |
| Minimum temperature | 14.9 | 14.1 | 16.9 | 18.6 | 15.4 | 13.7 | 13.9 | 14.7 | 14.5 | 14.1 | 15.5 | 15.3 | 15.6 | 16.1 | 16.4 | 16.1 | 16.7 | 17.2 | 16.8 | 15.1 | 16 | 15.8 | 13.1 | 10.7 | 11 | 11 | 10.9 | 12 | 11.8 | 12.4 |
| Apparent min temperature | 20.4 | 22.1 | 24.3 | 21.5 | 18.7 | 20 | 21.2 | 22.1 | 22.4 | 22.6 | 23.5 | 23.3 | 22.4 | 22.5 | 22.6 | 22.4 | 23.5 | 23.1 | 21.8 | 20.6 | 20 | 19.8 | 16.5 | 14 | 15.4 | 17.1 | 18.1 | 18.4 | 18.4 | 18.4 |
| September | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight duration (h) | 13.2 | 13.2 | 13.1 | 13.1 | 13 | 13 | 12.9 | 12.9 | 12.8 | 12.8 | 12.7 | 12.7 | 12.6 | 12.6 | 12.5 | 12.5 | 12.4 | 12.4 | 12.3 | 12.3 | 12.2 | 12.2 | 12.1 | 12.1 | 12 | 12 | 11.9 | 11.9 | 11.8 | 11.8 |
| Sunshine duration (h) | 12.1 | 11.9 | 11.9 | 10.9 | 11.9 | 11.8 | 11.8 | 11.8 | 11.8 | 11.7 | 11.7 | 11.7 | 8.5 | 10.6 | 11.4 | 11.3 | 11.5 | 7.7 | 10.8 | 0.2 | 10.1 | 3.5 | 11 | 10.8 | 10.9 | 10.9 | 10.9 | 10.8 | 10.8 | 10.7 |
| Precipitation (mm) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0.6 | 5.9 | 1.5 | 1.4 | 0 | 1.5 | 0 | 0.1 | 7.6 | 24.4 | 3.1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Precipitation hours | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 4 | 8 | 4 | 5 | 0 | 3 | 0 | 1 | 11 | 16 | 6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Wind speed (m/s) | 11.2 | 8.2 | 13.8 | 22.9 | 23.6 | 18.1 | 15.2 | 17.9 | 9.7 | 6.8 | 11.2 | 8.5 | 12.3 | 10.2 | 6.6 | 17.5 | 9.4 | 10.8 | 17 | 8 | 16.4 | 24.5 | 20.5 | 19.5 | 20.5 | 12.7 | 9.5 | 8.9 | 8 | 7.4 |
In September 2023, the highest daytime temperature in Siena was 31.1°C.
While the minimum temperature at night dropped to 10.7°C.
The average nighttime and daytime temperatures during September in Siena are 14.5°C and 26.8°C respectively.
The precipitation sum in September is about 46 mm.