Best time to visit Siena
Re-score for me — drag the dial — every chart on the page recolours live for your heat limit 27°C
Default 27 °C is the upper edge of the Holiday Climate Index "ideal comfort" band (Scott, Rutty, Amelung & Tang, 2016). Above this, most warm-tourism travellers report measurable discomfort.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
Greyed factors are scored normally — extreme heat overrides them, so a clear sky or low rain can't lift the period.
How is this scored? HCI / Steadman / CCI gate — full methodology and citations below.
Compare with another destination
Add as many as you like — stacked below the main strips above. Each row is just the recent-window score strip and (for beach destinations) sea-temperature strip.
Tours in Siena
8 top-rated tours via Viator. Booking links earn this site a commission at no cost to you.
- 1
VIP Chianti, Brunello wine & Pienza with lunch From Siena - 2
Siena Bites & Stories: A Tasty City Adventure with a Local - 3
Small Group E-Bike Chianti Tour with farm lunch from Siena - 4
Small-Group Arezzo and Cortona Day Trip from Siena - 5
Explore Siena Market & Cook at a Local’s Home by Cesarine - 6
Cooking Class in a historical Palace in Siena Provence - 7
Small-Group Brunello di Montalcino Wine-Tasting Trip from Siena - 8
Private Tour of Siena Cathedral
Last refreshed 2026-05-25.
Similar climatesFlorence94% · Rome93% · Bologna93%
Other destinations with the most-alike year-round climate to Siena (apparent temperature, rain hours, sunshine — matched within the same trip-profile). The ±N chip compares each match's typical score for the current month against Siena's. Based on the 2020-2024 climatology, not this year's actual weather.
Month-by-month
| Month | Temp °C | Feels °C | Rain days | Rain h | Rain h/day | Humidity | Wind km/h | Sun h | UV | Interest | Score |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | 2–10 | 8 | 9 | 118 | 13.1 | 75% | 15 | 149 | 1 | Quiet | 5 |
| Feb | 3–13 | 10 | 7 | 90 | 12.9 | 68% | 16 | 163 | 2 | Quiet | 6 |
| Mar | 4–15 | 12 | 8 | 101 | 12.6 | 59% | 16 | 214 | 3 | Quiet | 7 |
| Apr | 6–18 | 15 | 10 | 111 | 11.1 | 52% | 17 | 247 | 5 | Quiet | 8 |
| May | 11–23 | 21 | 11 | 118 | 10.7 | 52% | 17 | 269 | 6 | Quiet | 9 |
| Jun | 16–28 | 28 | 7 | 72 | 10.3 | 46% | 16 | 295 | 7 | Quiet | 9 |
| Jul | 19–33 | 33 | 4 | 26 | 6.5 | 37% | 17 | 326 | 8 | Quiet | 5 |
| Aug | 19–32 | 32 | 6 | 50 | 8.3 | 39% | 16 | 288 | 7 | Peak | 5 |
| Sep | 15–26 | 26 | 8 | 91 | 11.4 | 51% | 15 | 237 | 5 | Busy | 9 |
| Oct | 12–21 | 20 | 9 | 109 | 12.1 | 65% | 15 | 197 | 3 | Quiet | 8 |
| Nov | 7–15 | 13 | 10 | 103 | 10.3 | 72% | 15 | 158 | 2 | Busy | 7 |
| Dec | 4–11 | 9 | 12 | 155 | 12.9 | 79% | 14 | 132 | 1 | Moderate | 5 |
UV Index in Siena by Month
UV index in Siena peaks at 8 (high) in July, dropping to 1 (low) in January. June, July, August have high UV — SPF 30+ and sunglasses recommended.
Best months in detail
September
9/1015–26°C · 8 rain days (91h) · 237 sun hours · 51% humidity · Busy crowd · UV 5 (moderate) · sunniest 1 in 10 days reach 7 (high)
June
9/1016–28°C · 7 rain days (72h) · 295 sun hours · 46% humidity · Quiet crowd · UV 7 (high) · sunniest 1 in 10 days reach 9 (very high)
May
9/1011–23°C (feels 21°C) · 11 rain days (118h) · 269 sun hours · 52% humidity · Quiet crowd · UV 6 (moderate) · sunniest 1 in 10 days reach 7 (high)
Every month
Show the other 9 months in detail
January
5/102–10°C (feels 8°C) · 9 rain days (118h) · 149 sun hours · 75% humidity · Quiet crowd · UV 1 (low)
February
6/103–13°C (feels 10°C) · 7 rain days (90h) · 163 sun hours · 68% humidity · Quiet crowd · UV 2 (low)
March
7/104–15°C (feels 12°C) · 8 rain days (101h) · 214 sun hours · 59% humidity · Quiet crowd · UV 3 (moderate)
April
8/106–18°C (feels 15°C) · 10 rain days (111h) · 247 sun hours · 52% humidity · Quiet crowd · UV 5 (moderate) · sunniest 1 in 10 days reach 6 (high)
July
5/1019–33°C · 4 rain days (26h) · 326 sun hours · 37% humidity · Quiet crowd · UV 8 (high) · sunniest 1 in 10 days reach 9 (very high)
August
5/1019–32°C · 6 rain days (50h) · 288 sun hours · 39% humidity · Peak crowd · UV 7 (high) · sunniest 1 in 10 days reach 8 (very high)
October
8/1012–21°C · 9 rain days (109h) · 197 sun hours · 65% humidity · Quiet crowd · UV 3 (moderate)
November
7/107–15°C (feels 13°C) · 10 rain days (103h) · 158 sun hours · 72% humidity · Busy crowd · UV 2 (low)
December
5/104–11°C (feels 9°C) · 12 rain days (155h) · 132 sun hours · 79% humidity · Moderate crowd · UV 1 (low)
Frequently asked questions about visiting Siena
When is the best time to visit Siena?
September is the highest-scoring month (9/10 on the Holiday Climate Index). Typical conditions: 15–26°C (8 rainy days). The top three months by score are September, June, May.
What is the worst time to visit Siena?
December is the lowest-scoring month (5/10). Typical conditions: 4–11°C (12 rainy days).
Is Siena too hot in summer?
2 months (July, August) trip the heat deal-breaker in our scoring: apparent temperature crosses the comfort cap, so even with clear skies and low rain the score is held down. Plan around it if heat tolerance is low.
When are crowds lowest in Siena?
Search-interest seasonality (Google Trends 2021-2025) is lowest in February and peaks in August. Interest tracks both in-trip visitors and lead-time planners, so treat it as a "destination is on people's minds" signal rather than literal arrivals.
Which months in Siena have good weather but fewer tourists?
May (climate 9/10, crowd index 19) and June (climate 9/10, crowd index 19) — shoulder months with above-average climate and below-median search-interest. Often the best value-for-weather trade.
What is the UV index in Siena by month?
UV peaks at 8 (high) in July and is lowest in January at 1 (low). Monthly peak values: Jan 1, Feb 2, Mar 3, Apr 5, May 6, Jun 7, Jul 8, Aug 7, Sep 5, Oct 3, Nov 2, Dec 1.
What is the UV index in Siena in July?
July is the peak UV month in Siena, with a daily-peak UV index of 8 (high). Apply SPF 30+, wear sunglasses, and seek shade during midday hours.
How high can UV get in Siena on the sunniest days?
Most days look like the monthly average, but on the sunniest ~1 in 10 days UV climbs higher than the mean suggests. July is the worst case: typical days average UV 8 (high), but the top 10% of days reach UV 9 (very high) — and even higher. Months where the sunniest days routinely exceed the typical reading: April, May, June, July, August, September. Plan sun protection for the worst case, not the average.
Is air quality in Siena bad for travelers?
PM2.5 (fine-particle pollution) exceeds the WHO sensitive-group guideline (15 µg/m³) in 4 months: January, February, March, December. The worst month is February with a typical-day mean of 14 µg/m³ (moderate); on the worst 10% of days PM2.5 reaches 22 µg/m³ (unhealthy for sensitive) and higher. People with asthma, heart conditions, or sensitive children may want to avoid these months or limit outdoor activity. Source: CAMS via Open-Meteo.