May 18 is generally a great time to visit Siena. While there is a slight chance of rain (29%), showers are usually brief. Expect comfortable 21°C weather. Expect a bustling atmosphere in Siena right now—this is when the city truly comes alive with visitors.
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Essential Travel Info for Siena
Currency
EUR
€ Euro
Language
Italian
+1 more
Driving
Right side
Safety
High Safety
GPI: 1.643
Siena Weather Forecast for May 18
"Mild & Comfortable. Expect average highs of 21.3°C. 29% chance of rain."
What to Wear in Siena in May
Based on historical data for May 18, Siena typically experiences temperatures between 10.7°C and 21.3°C. We recommend packing light jacket, long pants to stay comfortable. With a 29% chance of rain, keeping a raincoat or umbrella handy is a smart move.
Complete Packing Guide
Weekly breakdown & essential items for Siena
Smart Suitcase
- Light Jacket
- Long Pants
Average High
21.3°C
Daytime Peak
Average Low
10.7°C
Nighttime Low
Feels Like
21.5°C
☀️ Feels accurate
Rain Chance
29%
Avg 1.6mm if it rains
Cloud Cover
51%
Overcast
Pressure
1014.4 hPa
Medium volatility
Siena Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
🎯 This date historically delivers consistent weather 89% of the time. Safe to plan outdoor activities with confidence.
Sun Exposure
UV Index & Safety Guide
Protection Needed
SPF 30 recommended
04:00 - 10:00
16:00 - 19:00
Type I-II
🔴 15 min to burn
Type III-IV
🟡 23 min to burn
Type V-VI
🟢 38 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
15.8°C
Pleasant
Heat Stress
Low
No heat warning
😊 Best outdoor time:
Any time during daylight hours
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in Italy
Flight Traffic
High
98/100 pressure index
Health Advisory
Required
1 vaccine • View Details →
Landing Slots
~63
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Siena
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
04:49
☀️ Noon
12:12
🌇 Sunset
19:35
⏱️ Daylight
14h 46m
Wind Speed
14.2 km/h
Gentle breeze
Sunshine
11.5 hrs
Direct Sun (Cloud-free)
Humidity
71%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Siena
Smart Flight Estimator
Airport-to-Airport Logistics
unlock smart flight estimates
Add your home location in settings to see airport details.
Travel Health & Safety in Siena
Travel Comfort Index
Real-time tourism conditions
Weather Quality
⛅ Good
Tourist Crowds
🟡 Busy
Price Level
💰💰💰 Expensive
Health & Wellbeing
Meteo-Health Forecast
Moderate fluctuations. Some sensitivity possible.
Weather unlikely to affect joint pain.
Moderate fish activity expected.
Air quality is acceptable. Sensitive individuals should limit prolonged outdoor exertion.
Regional Safety Profile
Seismic Activity
Moderate seismic activity. Occasional tremors possible.
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Siena on May 18 averages 21.3°C with a 29% precipitation probability. Wedding/Outdoor Event Score: 96/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Siena Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Better Alternatives Nearby
Consider these dates within ±7 days
May 24
23°C • 16% rain
Score
100
May 25
23.4°C • 14% rain
Score
100
May 11
21.2°C • 19% rain
Score
99
💡 Moving your event by a few days could significantly improve weather conditions
Compare Other Cities
Same date (May 18) in other destinations
🌍 Explore the same date in different destinations around the world
📍 Is Siena Worth Visiting on May 18?
Planning a trip to Siena on May 18? Our historical weather analysis based on 30 years of NASA satellite data shows that this time of year is characterized by pleasant mild weather averaging 21.3°C with a 29% historical precipitation risk.
✈️ Travel Logistics: Approximately 63 landing slots available daily during this period, indicating manageable crowd levels.
💉 Health Advisory: 7 vaccinations are recommended for Italy, including COVID-19.
📊 Historical Extremes: The hottest May 18 recorded in the last 30 years saw temperatures hit 29.1°C in 2022, while the coldest dropped to 7.8°C in 2021.