Siena Weather in September
Siena in September sees high temperatures, with highs around 26°C (79°F) and overnight lows of 14°C (57°F). Rainfall is fairly high at around 97 mm (3.8 in) on average, so pack waterproofs just in case.
Rainfall in Siena in September
Rain is expected on roughly 9 days, totalling around 97 mm (3.8 in) for the month. When showers do arrive, they tend to be on the heavier side. Worth being prepared even if rain days are not that numerous.
Temperature in Siena in September
Siena in September is worth a visit. The temperature is perfect, with 26°C (79°F) during the day and 14°C (57°F) at night. Overall, the month follows a fairly predictable daily temperature pattern. Nights drop to around 14°C (57°F), which is noticeably cooler than the daytime. A light jacket for the evening is a sensible addition, and the cool nights tend to make sleeping comfortable.
Sunshine in Siena in September
The month enjoys around 220 hours of sunshine, creating mostly sunny days with good weather conditions.If your ideal day consists of dry skies and pleasant temperatures, May, June and September typically offer the best circumstances for Siena.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Italy, check out our Siena's climate page.
Siena Temperature in September
Min Temperature
14°C (57°F)
Max Temperature
26°C (79°F)
Chance of Rain
30%
Precipitation
97 mm (3.8 in)
Rainy days
9 days
Sunshine
220 hours
Percentage Sunshine
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Siena typically drop from around 28°C (82°F) at the start of September to approximately 24°C (75°F) by the end. Nights are pleasant, with lows typically ranging from 13°C (55°F) to 16°C (61°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for Siena in September
Browse day-by-day weather records for Siena spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Siena historical weather extremes in September
Based on weather observations in Siena between 1976 and 2025, these are the recorded extremes during September.
- The hottest September day on record in Siena reached 35°C (95°F) (September 1, 2024).
- The coldest September day was on September 27, 2020, with a maximum of 14°C (57°F).
- The lowest overnight temperature recorded in September was 4°C (39°F) (September 21, 1978).
Best Places in Italy in September
Find out more about the weather in Italy and which places have the best travel conditions in this month. See all of Italy in September →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in Siena in September
Warm weather calls for comfortable, breathable clothing in September. Cotton t-shirts, shorts, light dresses, and sandals are perfect. You might still want a light layer for evenings or air-conditioned places (for example buses). High rain levels are expected, so pack waterproof gear and an umbrella or poncho. Don't forget sun protection, sunglasses, sunscreen, and a hat. These are all good ideas with this much sunshine.What To Do in Siena in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Italy, check out our Siena's climate page.
See the full Siena climate overview or explore weather in Italy.
