September · Italy
Best time to visit Siena in September Weather, crowds & prices
Weather in Siena in September
Average temperature 20°C, 101 mm of rain, about 27 days with 6+ hours of sunshine and 71% humidity — based on the five most recent complete years of ERA5 data (2021–2025).
September score
8.2/10
Ranked #4 of 12 months
- Avg temp
- 20°C
- Rainfall
- 101 mm
- Humidity
- 71%
- Days with 6h+ sun
- 27
- Crowd Density
- Moderate Crowds
- Average Expenses
- $$ · Moderate Cost ($$)
September in Siena scores 8.2/10 for sightseeing and cultural travel - an above-average month (#4 of 12). Expect around 20°C, 101 mm of rain, and roughly 27 days with 6+ hours of sunshine this month.
Siena's medieval center revolves around Piazza del Campo, framed by the Palazzo Pubblico and the Torre del Mangia.
September holds up well in Siena — 4th best month
September averages 20°C (68°F) — pleasant for mornings and evenings on foot in the city, with a midday break when the sun is strongest.
Monthly rainfall reaches 101 mm — wet for this destination — but about 27 days with 6+ hours of sunshine still break through, so keep one indoor fallback in the plan.
It scores 8.2/10 here, 4th of 12 months, against 9.3/10 in the destination's best month.
Pack light clothing, a hat and real sun protection, a proper rain shell rather than an umbrella.
Plan for mid-season pricing, with crowds are moderate.
Frequently asked
- What is the weather like in Siena in September?
- In September, Siena averages 20°C, 101 mm of rain, and about 27 days with 6+ hours of sunshine. Its climate-comfort score is 8.2/10.
- Is September a good time to visit Siena?
- September earns a 8.2/10 climate-comfort score. Use the year-round chart to weigh the weather against your budget and crowd preferences.
- How much does it rain in Siena in September?
- Expect about 101 mm of rain in September. Average humidity is 71% and there are about 27 days with 6+ hours of sunshine.
Curated in Siena
Tickets & experiences
Things to do in Siena
Siena, Italy. Live activities and tours from GetYourGuide, matched to this destination.