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Weather in Siena for September 2025

Your guide to Siena weather in September - trends and predictions

    Temperatures

  • Until now, September 2025 in Siena is slightly cooler than the historical average by -1.9 °C.

  • Expect cooler weather in the next days in Siena with the forecast suggesting a temperature of 25.4 °C, lower than the historical average.

  • In general, the average temperature in Siena at the beginning of September is 29.1 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 21.9 °C by the end of September.

    • Rain 🌧️

  • The climate of Siena in September is notably wet, with an average of 14 rainy days, and a total of 96.9 mm of precipitation.

    • More

  • Is September a good time to visit Siena? check out the best time to travel to Siena page.

  • New! Chat with our AI weatherman - it’s amazing and free.

Average dry days
16
Dry days
Average rainy days
14
Rainy days
Average snowy days
0
Snow days
Average temperatures
26°/14°
Temperatures
Average wind speed
16 km/h
Avg max wind
Average humidity
65 %
Avg humidity

Siena Weather September

Move between months or click on a day
August
October
Mon.Tue.Wed.Thu.Fri.Sat.Sun.
1
Sunny
32°
2
Thundery outbreaks possible
28°
3
Patchy rain possible
28°
4
Patchy rain possible
30°
5
Patchy light rain with thunder
27°
6
Patchy rain possible
28°
7
Patchy rain possible
31°
8
Sunny
28°
9
Sunny
28°
10
Sunny
27°
11
Patchy rain possible
29°
12
Sunny
27°
13
Partly cloudy
23°
14
Partly cloudy
25°
15
Sunny
28°
16
Sunny
28°
17
Sunny
26°
18
Sunny
28°
19
Sunny
30°
20
Sunny
30°
21
Sunny
29°
22
Sunny
28°
23
Patchy rain possible
25°
24
Moderate rain
22°
25
Patchy rain possible
21°
26
Partly cloudy
18°
27
Sunny
21°
28
Sunny
22°
29
Sunny
24°
30
Sunny
25°

Temperatures trend during September in Siena

See the weather trend as well as the moving average line

September weather in Siena day by day

Click on a date for more information
August October
Date Weather Temperatures Rain UV More
1 Sept. Sunny
Sunny
 32° /16° 0 mm 8
2 Sept. Thundery outbreaks possible
Thundery outbreaks possible
 28° /15° 4.8 mm 6
3 Sept. Patchy rain possible
Patchy rain possible
 28° /15° 0.4 mm 7
4 Sept. Patchy rain possible
Patchy rain possible
 30° /15° 1.1 mm 7
5 Sept. Patchy light rain with thunder
Patchy light rain with thunder
 27° /15° 5.6 mm 7
6 Sept. Patchy rain possible
Patchy rain possible
 28° /15° 0.1 mm 7
7 Sept. Patchy rain possible
Patchy rain possible
 31° /14° 0 mm 8
8 Sept. Sunny
Sunny
 28° /15° 14.1 mm 7
9 Sept. Sunny
Sunny
 28° /15° 13.8 mm 7
10 Sept. Sunny
Sunny
 27° /14° 16.9 mm 7
11 Sept. Patchy rain possible
Patchy rain possible
 29° /14° 0.8 mm 7
12 Sept. Sunny
Sunny
 27° /13° 7.9 mm 6
13 Sept. Partly cloudy
Partly cloudy
 23° /12° 2.3 mm 6
14 Sept. Partly cloudy
Partly cloudy
 25° /12° 0.2 mm 6
15 Sept. Sunny
Sunny
 28° /15° 0 mm 1.5
16 Sept. Sunny
Sunny
 28° /16° 0 mm 1.2
17 Sept. Sunny
Sunny
 26° /15° 0 mm 1.4
18 Sept. Sunny
Sunny
 28° /13° 0 mm 1.5
19 Sept. Sunny
Sunny
 30° /15° 0 mm 1.6
20 Sept. Sunny
Sunny
 30° /16° 0 mm 6
21 Sept. Sunny
Sunny
 29° /17° 0 mm 6
22 Sept. Sunny
Sunny
 28° /15° 0 mm 6
23 Sept. Patchy rain possible
Patchy rain possible
 25° /16° 4.2 mm 4
24 Sept. Moderate rain
Moderate rain
 22° /18° 11.1 mm 4
25 Sept. Patchy rain possible
Patchy rain possible
 21° /13° 1.5 mm 4
26 Sept. Partly cloudy
Partly cloudy
 18° /10° 0 mm 4
27 Sept. Sunny
Sunny
 21° /10° 0 mm 4
28 Sept. Sunny
Sunny
 22° /10° 0 mm 5
29 Sept. Sunny
Sunny
 24° /10° 0 mm 6
30 Sept. Sunny
Sunny
 25° /10° 0 mm 7
Next
Important Notice
Our weather forecast for Siena in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Siena forecast closer to your planned date for the most up-to-date weather information.
Change Month
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Siena weather in September vs August vs October

Compare September weather in Siena with the previous and following months. See how temperature, rainfall, wind, and other conditions change throughout the year to help you plan your visit.
AugustSeptemberOctober
WeatherSunny
Sunny
Patchy rain possible
Patchy rain possible
Patchy rain possible
Patchy rain possible
Temperatures35°/19°26°/14°21°/12°
Rainfall48 mm97 mm119 mm
Wind17.8 km/h15.8 km/h13.9 km/h
Humidity54%65%77%
Rainy days7 days14 days19 days
Dry days24 days16 days12 days

Planning a trip to Siena? Discover the best time to visit

Siena in September - FAQ

What are the expected maximum and minimum temperatures in Siena during September?
Enjoy moderate daytime temperatures of up to 26° and cooler nights around 14°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Siena during September?
Moderate rainfall is anticipated in Siena during September, with a total of 96.9 mm spread over approximately 14 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Siena during September?
The average wind speed in Siena during September is 16 km/h, suggesting breezy to windy conditions, depending on your activities.

What to pack to Siena in September?

As you prepare for your trip to Siena in September, it's important to consider the typical weather patterns for the time of year. Below is a carefully tailored packing list to ensure that your time in Siena, during September, is comfortable and enjoyable, regardless of the weather conditions.

  • Clothing
    • Lightweight Clothing: T-shirts, blouses, shorts, skirts
    • Rain Gear: Lightweight, waterproof clothing
  • Footwear
    • Waterproof Shoes
  • Accessories
    • Sunglasses: For sun protection
    • Sun Hats: Wide-brimmed hats for sun protection in warm weather
    • Scarves: To protect you from the cold wind
    • Gloves/Mittens: Essential for cold weather
    • Warm Hats: Warm hats for insulation in cold weather
    • Umbrellas/Raincoats: For rainy days
  • Personal Items
    • Sunscreen: High SPF for sunny destinations
    • Lip Balm with SPF: To protect against chapped lips

September rainfall patterns in Siena

Explore the daily rainfall trends and prepare for Sienas September weather 💧

UV exposure in Siena during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️

Quick links

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Get accurate weather forecasts for Siena, located at latitude 43.318 and longitude 11.331. Stay updated with localized weather information tailored for Siena.

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