Siena, Italy climate
Cfa Humid subtropical
Siena has a seasonal mild-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is July with an average daily high near 31°C, while the coldest is January averaging around 0°C at night. Around 865 mm of precipitation falls each year, peaking in November (121 mm) and easing off in July (42 mm).
☀️
Summers
Hot
Highs near 31°C in July.
❄️
Winters
Chilly
Lows near 0°C in January.
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Rain
Moderate rainfall
About 865 mm of rain a year.
Wettest in November
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Sky & trend
Partly cloudy
A roughly even mix of sun and cloud.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresHours of sunshine per day
Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER)Siena climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 9 | 11 | 15 | 19 | 23 | 28 | 31 | 32 | 26 | 20 | 14 | 10 |
| Avg temp (°C) | 5 | 6 | 9 | 12 | 17 | 21 | 24 | 24 | 19 | 14 | 9 | 5 |
| Avg low (°C) | 0 | 1 | 3 | 6 | 10 | 13 | 15 | 16 | 12 | 9 | 5 | 1 |
| Precipitation (mm) | 53 | 57 | 64 | 71 | 74 | 53 | 42 | 43 | 96 | 109 | 121 | 82 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 9 | 11 | 15 | 19 | 23 | 28 |
| Avg temp (°C) | 5 | 6 | 9 | 12 | 17 | 21 |
| Avg low (°C) | 0 | 1 | 3 | 6 | 10 | 13 |
| Precipitation (mm) | 53 | 57 | 64 | 71 | 74 | 53 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 31 | 32 | 26 | 20 | 14 | 10 |
| Avg temp (°C) | 24 | 24 | 19 | 14 | 9 | 5 |
| Avg low (°C) | 15 | 16 | 12 | 9 | 5 | 1 |
| Precipitation (mm) | 42 | 43 | 96 | 109 | 121 | 82 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 65 | 61 | 62 | 65 | 62 | 50 | 36 | 39 | 53 | 62 | 69 | 65 |
| Relative humidity (%) | 91 | 86 | 82 | 78 | 73 | 63 | 54 | 55 | 68 | 80 | 89 | 91 |
| Wind speed (mph) | 5.4 | 5.8 | 6.0 | 5.3 | 4.8 | 4.5 | 4.7 | 4.4 | 4.7 | 4.9 | 5.2 | 5.4 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 65 | 61 | 62 | 65 | 62 | 50 |
| Relative humidity (%) | 91 | 86 | 82 | 78 | 73 | 63 |
| Wind speed (mph) | 5.4 | 5.8 | 6.0 | 5.3 | 4.8 | 4.5 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 36 | 39 | 53 | 62 | 69 | 65 |
| Relative humidity (%) | 54 | 55 | 68 | 80 | 89 | 91 |
| Wind speed (mph) | 4.7 | 4.4 | 4.7 | 4.9 | 5.2 | 5.4 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from the WMO's CLINO 1991–2020 collection, measured at Arezzo, about 45 km from the city centre.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.