Siena records about 760mm of rain across roughly 78 wet days a year, which is a 21% chance on an average day. November is the wettest month at 82mm (11% of the annual total) and July the driest at 22mm. Local rain type: brief showers. Siena has a classic Tuscan climate — dry summers and wetter autumn. The Palio horse race in July and August runs in virtually guaranteed dry weather.
Chance of rain on an average day: 21%
Rainfall climatology for Siena. The live hour-by-hour answer for today loads at the top of this page from Open-Meteo and refreshes through the day — the figures below describe a typical year, not today.
Last updated: · Live forecast data refreshes hourly.
| Annual rainfall | 760mm |
| Rain days per year | 78 |
| Odds on an average day | 21% |
| Wettest month | November — 82mm over 10 days |
| Driest month | July — 22mm over 3 days |
| Rain type | brief showers |
| Best dry window | June through August offers dry conditions for Palio and sightseeing. |
| Worst rain window | November brings the heaviest rainfall. |
November delivers 273% more rain than July (82mm vs 22mm). That gap is the difference between planning around showers and ignoring them.
No single month holds more than 11% of the annual total, so rain in Siena is spread through the year — there is no season you can rely on being dry.
Siena rain typically comes as discrete showers, so a compact umbrella and a flexible plan are usually enough.
Rain falls on about 10 days in November against 3 in July — the frequency swing matters more for planning than the millimetre totals.
Climate normals. Use them to judge whether today's live forecast at the top of the page is typical or unusual for the season.
| Month | Rainfall | Rain days | Chance on a given day | Highs |
|---|---|---|---|---|
| January | 48mm | 6 | 20% | 8°C |
| February | 42mm | 5 | 17% | 8°C |
| March | 52mm | 7 | 23% | 11°C |
| April | 58mm | 7 | 23% | 17°C |
| May | 56mm | 7 | 23% | 22°C |
| June | 38mm | 5 | 17% | 28°C |
| July | 22mm | 3 | 10% | 31°C |
| August | 28mm | 4 | 13% | 31°C |
| September | 55mm | 7 | 23% | 28°C |
| October | 72mm | 9 | 30% | 22°C |
| November | 82mm | 10 | 33% | 17°C |
| December | 62mm | 8 | 27% | 11°C |
Rain probability is the chance that at least 0.2mm falls at your location — not how long it rains. For Siena we combine the hourly probability curve, expected volume in millimetres, and the city's own rainfall record into a single umbrella verdict.
| Factor | Weight | What it measures |
|---|---|---|
| Hourly probability | 40% | Peak and sustained chance of measurable rain across the next 24 hours. |
| Expected volume | 30% | Total millimetres, which separates a passing shower from a genuine soaking. |
| Timing & duration | 20% | When rain starts, when it eases, and the longest continuous dry window. |
| Local rain type | 10% | Drizzle, brief showers, thunderstorms or monsoon — each needs different gear. |
Live hourly values come from Open-Meteo and refresh through the day. Monthly rainfall figures are climate normals, so they describe a typical year rather than a forecast.
Siena records rain on roughly 78 days a year — about a 21% chance on any given day — totalling around 760mm.
November, with about 82mm over 10 rain days. That is 11% of the entire year's rainfall in a single month.
July is the driest month at 22mm across roughly 3 days. June through August offers dry conditions for Palio and sightseeing.
Siena has a classic Tuscan climate — dry summers and wetter autumn. The Palio horse race in July and August runs in virtually guaranteed dry weather.
No. Probability is the chance that at least 0.2mm of rain falls at your location at some point in the period. Check the expected millimetres alongside it: 40% with 0.4mm is a passing shower, 40% with 12mm is a soaking.