Siena climate — normals and trends
Siena (Italy) has a hot-summer mediterranean climate (Csa) under the Köppen-Geiger classification. Its mean annual temperature is 13.3 °C and it receives 870 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (23.0 °C on average) and the coldest is January (4.5 °C). Rainfall peaks in November.
Siena averages 39 frost days, 28 hot days (≥ 30 °C) and 112 rainy days per year.
Siena has warmed by +1.8 °C between 1940 and 2025, or +0.22 °C per decade. This trend is statistically significant.
The number of frost days there went from about 53 to 25 per year over the period.
The hottest day of the period reached 38.0 °C (on 31 July 2024) and the coldest -23.6 °C (on 15 February 1956).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
SienaTuscany
- coords
- 43.32°, 11.33°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
13.3°C
Average daily high
18.2°C
Average daily low
8.8°C
Annual rainfall
870mm
Sunshine / day
9.6h
Mean relative humidity
75%
Average peak wind
13.4km/h
Seasonal range
18.5°C
Frost days (< 0 °C)
39 d/yr
Hot days (≥ 30 °C)
28 d/yr
Rainy days (≥ 1 mm)
112 d/yr
Annual snowfall
11.3 cm
Average feels-like high
17.2 °C
Average feels-like low
7.4 °C
Average peak gust
32.5 km/h
Tropical nights (≥ 20 °C)
7 d/yr
Solar radiation
14.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.8 °C
since 1940
+0.2 °C per decade · r² = 0.48 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
38.0 °C
31 July 2024
Coldest day
-23.6 °C
15 February 1956
Wettest day
142 mm
4 November 1966
Windiest day
39.4 km/h
29 August 2003
Strongest gust
106.6 km/h
29 October 2018
Hottest feels-like
41.6 °C
10 August 2024
Coldest feels-like
-28.2 °C
15 February 1956
Snowiest day
19.0 cm
1 February 2012
Sunniest day
14.9 h
7 July 1941
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 11.2 °C | +2.9 °C | 49 mm | -13 mm |
| Feb | 12.2 °C | +2.1 °C | 123 mm | +51 mm |
| Mar | 15.1 °C | +1.8 °C | 125 mm | +49 mm |
| Apr | 18.8 °C | +2.1 °C | 77 mm | -6 mm |
| May | 22.0 °C | +0.9 °C | 93 mm | +19 mm |
| Jun | 31.0 °C | +5.6 °C | 7 mm | -44 mm |
| Jul | 30.1 °C | +1.2 °C | 47 mm | +16 mm |
| Aug | 30.9 °C | +2.0 °C | 64 mm | +17 mm |
| Sep | 25.4 °C | +0.9 °C | 103 mm | +18 mm |
| Oct | 19.9 °C | +0.8 °C | 55 mm | -47 mm |
| Nov | 14.5 °C | +1.3 °C | 73 mm | -35 mm |
| Dec | 11.1 °C | +1.9 °C | 59 mm | -23 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Siena?
Siena has a hot-summer mediterranean climate (Köppen Csa). Over 1940-2025, the average annual temperature is 13.3 °C and it receives 870 mm of precipitation per year.
What is the hottest day ever recorded in Siena?
The hottest day measured in Siena between 1940 and 2025 was 31 July 2024, reaching 38.0 °C.
What is the coldest day in Siena?
The coldest day measured in Siena between 1940 and 2025 was 15 February 1956, at -23.6 °C.
Does it snow in Siena?
Yes. Siena gets on average 11.3 cm of snow per year and has around 39 frost days.
Has the climate of Siena warmed?
Yes: Siena warmed by +1.8 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Siena?
The wettest day measured in Siena between 1940 and 2025 was 4 November 1966, with 142 mm of rain in 24 hours.
What was the windiest day in Siena?
The windiest day measured in Siena between 1940 and 2025 was 29 August 2003, with winds reaching 39.4 km/h.
What is the warmest month in Siena?
The warmest month in Siena is July (23.0 °C on average); the coldest is January (4.5 °C).
How much does it rain in Siena?
Siena receives on average 870 mm of precipitation per year, spread over about 112 rainy days.
Is it sunny in Siena?
Siena gets on average 9.6 hours of sunshine per day, roughly 3,504 hours per year over 1940-2025.
What is the biggest single-day snowfall in Siena?
The heaviest 24-hour snowfall measured in Siena between 1940 and 2025 was 1 February 2012, with 19.0 cm.
Are there tropical nights in Siena?
Yes: Siena has on average 7 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Siena?
In Siena, between 1940 and 2025, the highest apparent temperature reached 41.6 °C on 10 August 2024, and the lowest was -28.2 °C on 15 February 1956.
Compare Siena with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Siena