The best months to visit Siena are April, May, June, September and October, when average highs land in the comfortable 20s and the city feels relaxed. October brings highs around 20.7 °C with 9 rain days, while June warms to 28.4 °C with just 7 rain days, so you can linger in Piazza del Campo without the summer heat. July and August are peak season, driven by school-holiday crowds and higher prices, and are also the hottest months at 31.7 °C. Winter is the quiet low season, cool and often damp but ideal if you want Siena largely to yourself.
Best months AprilMayJuneSeptemberOctober
Siena month by month
Average highs and lows (°C), 2016–2025. Highlighted bars are the best months.
| Month | High | Low | Rain days | Sunshine | Days ≥30 °C | Crowds |
|---|---|---|---|---|---|---|
| January | 10 °C | 1.9 °C | 9 | ●●●●● | – | ●●●●● |
| February | 12.3 °C | 3.1 °C | 9 | ●●●●● | – | ●●●●● |
| March | 14.5 °C | 4.3 °C | 9 | ●●●●● | – | ●●●●● |
| April | 18.3 °C | 7.1 °C | 10 | ●●●●● | – | ●●●●● |
| May | 21.8 °C | 11.1 °C | 13 | ●●●●● | – | ●●●●● |
| June | 28.4 °C | 16.1 °C | 7 | ●●●●● | 12 | ●●●●● |
| July | 31.7 °C | 18.7 °C | 5 | ●●●●● | 22 | ●●●●● |
| August | 31.7 °C | 18.8 °C | 6 | ●●●●● | 22 | ●●●●● |
| September | 25.8 °C | 14.9 °C | 9 | ●●●●● | 4 | ●●●●● |
| October | 20.7 °C | 11.1 °C | 9 | ●●●●● | – | ●●●●● |
| November | 14.6 °C | 6.6 °C | 12 | ●●●●● | – | ●●●●● |
| December | 11 °C | 3.2 °C | 11 | ●●●●● | – | ●●●●● |
How the months are picked.A month qualifies when its average high sits in the comfortable 20–28 °C band (scored down towards 9 °C and 37 °C), rain days are few and sunshine hours are high — at least 78 % of the city's best-scoring month. July and August are then set aside as peak season (school-holiday crowds and prices) whenever at least three other months qualify; where summer is the only comfortable window they stay. Figures are ten-year averages (2016-01-01 to 2025-12-31) from ERA5 reanalysis data via Open-Meteo (CC BY 4.0) for the city centre coordinates. Sunshine is shown relative to the city's own year (modelled data overstates absolute hours).Heat and sea: days with a high of 30 °C or more are averaged over 2016–2025 (ERA5).Crowds:Relative to an average month in the same region (Eurostat nights spent at tourist accommodation, by NUTS 2 region and month) — a measure of season, not of how crowded one city is compared with another. Busiest month August, quietest January; NUTS 2 region ITI1, 2022–2025, Eurostat.
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When to go, and what to expect
Spring (Mar–May)
Excellent for sightseeing and countryside views; pack for occasional showers.
Summer (Jun–Aug)
June is the sweet spot at 28.4 °C; July and August suit those who don't mind heat and queues.
Autumn (Sep–Nov)
September and October are superb; November turns wetter and dimmer.
Winter (Dec–Feb)
Worth it for atmospheric, crowd-free wandering if you accept the chill.
Notable events
- July and August
- Palio di Siena horse race in Piazza del Campo
- March or April
- Easter celebrations
- Summer
- Siena Jazz Festival
- December
- Christmas markets and festivities
Frequently asked
Is Siena too hot in August?
August is the hottest stretch, with average highs of 31.7 °C and lows near 18.8 °C. It's manageable but warm, and combined with peak crowds many travellers prefer June at 28.4 °C or September at 25.8 °C.
What is the rainiest month in Siena?
May records the most rain days at 13, closely followed by November with 12 and December with 11. Summer is driest, with July seeing just 5 rain days.
Is winter worth visiting Siena?
Winter is cool and damp, with January highs around 10 °C, lows of 1.9 °C and December the least sunny month. It's the quietest time, so it rewards travellers who want Siena without the crowds.
Know when to go? Now decide where to stay — our Siena area guide →
Areas of Siena
Best time to visit near here
Sources
- Open-Meteo historical weather API — monthly climate normals, 2016–2025 (CC BY 4.0)
- ERA5 reanalysis (ECMWF / Copernicus) — the underlying temperature, precipitation and sunshine data
- ReasonStay methodology — how the best months are computed and checked
An independent guide to Siena — honest, verified, no invented data. Climate figures: ERA5 via Open-Meteo, 2016–2025 averages; the best months are computed from them, not opinion.