Siena weather in September
Temperature, rain and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Excellent
Best time to visit: May – September
What is the weather like in Siena in September?
In September, Siena is warm: daytime highs average 24 °C, and nights cool down to about 14 °C. The sun shines for around 7 hours a day. Rain is frequent, with about 9 rainy days and 96 mm in total. All in all, September is an excellent month for a holiday in Siena.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 80 | 83 | 75 |
| Day | 29° | 24° | 19° |
| Night | 18° | 14° | 10° |
| Sun | 9 h | 7 h | 5 h |
| Rain days | 7 | 9 | 10 |
More details for September
- Daylight
- 12 h 34 min06:53 – 19:27
- UV index
- 6 · highclear sky, noon (estimate)All months
- Muggy days
- 1 daydew point 18 °C or moreAll months
- Wind
- 13 km/haverage daily peakAll months
- Cloud cover
- 45 %on averageAll months
- Hot days
- 1 day30 °C or moreAll months
- Snow days
- 0 days1 cm or more of fresh snow
- Time zone
- UTC+2Europe/Rome
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %70 %
- Few rainy daysweight 30 %64 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in September
- Sunscreen
- A jumper for the evenings
- Rain jacket or umbrella
Siena in September: quick answers
Is Siena hot in September?
Warm rather than hot: in September, daytime highs in Siena average 24 °C and nights cool to about 14 °C. On about 1 days the thermometer climbs to 30 °C or more.
Does it rain much in Siena in September?
Rain is frequent, with about 9 rainy days and 96 mm in total.
Siena month by month
The whole year in SienaAll destinations: ItalyWhere to go in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences