Siena weather in August
August in Siena: hot, a little rain, with clean air — an excellent time to visit.
#5 of 12 months in Siena · #358 of 897 destinations to visit in August · comfort 85/100 (tier A)
Updated June 2026 · climate normals from ERA5 reanalysis
Traveller notes on Siena in August
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Siena climate normals — August
| Daytime high | 30°C / 86°F | 🥵 hot |
|---|---|---|
| Nighttime low | 19°C / 66°F | |
| Rainfall | 54 mm / 2.1 in | 🌦 some rain |
| Rainy days | 7 days | |
| Humidity | 62% | 💧 humid |
| Dew point | 16°C / 60°F | |
| Sunshine | 12.2 h/day | |
| Daylight | 13.9 h | |
| Wind | 13 km/h / 8 mph | |
| Air quality (US AQI) | 47 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Siena in August — FAQ
- Is August a good time to visit Siena?
- August in Siena: hot, a little rain, with clean air — an excellent time to visit. It ranks #5 of 12 months for Siena on SeasonMap's comfort score (85/100).
- What is the weather like in Siena in August?
- In August, Siena averages a daily high of 30.1°C and a low of 18.7°C, with about 54 mm of rain over roughly 7 rainy days.
- What is the air quality in Siena in August?
- Siena has a mean US Air Quality Index of about 47 in August.