September 18 is statistically one of the best days of the year in Sintra. With minimal rain risk (13%) and pleasant highs of 23°C, it's ideal for outdoor adventures. As it's peak season for Sintra, we recommend booking your stay well in advance to secure the best rates.
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Essential Travel Info for Sintra
Currency
EUR
€ Euro
Language
Portuguese
Driving
Right side
Safety
Very High Safety
GPI: 1.301
Sintra Weather Forecast for September 18
"Mild & Comfortable. Expect average highs of 22.5°C. 13% chance of rain."
What to Wear in Sintra in September
Based on historical data for September 18, Sintra typically experiences temperatures between 16.6°C and 22.5°C. We recommend packing t-shirt, light clothing to stay comfortable. Trends suggest it will stay mostly dry (13% rain probability), but checking the forecast before heading out is always wise.
Complete Packing Guide
Weekly breakdown & essential items for Sintra
Smart Suitcase
- T-Shirt
- Light Clothing
Average High
22.5°C
Daytime Peak
Average Low
16.6°C
Nighttime Low
Feels Like
23°C
☀️ Feels accurate
Rain Chance
13%
Avg 0.7mm if it rains
Cloud Cover
36%
Overcast
Pressure
1016 hPa
Medium volatility
Sintra Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
🎯 This date historically delivers consistent weather 82% of the time. Safe to plan outdoor activities with confidence.
Sun Exposure
UV Index & Safety Guide
Protection Needed
SPF 30 recommended
07:00 - 10:00
16:00 - 19:00
Type I-II
🔴 22 min to burn
Type III-IV
🟡 33 min to burn
Type V-VI
🟢 55 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
18.5°C
Noticeable
Heat Stress
Low
No heat warning
🙂 Best outdoor time:
Any time during daylight hours
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in Portugal
Flight Traffic
High
87/100 pressure index
Health Advisory
Required
1 vaccine • View Details →
Landing Slots
~297
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Sintra
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
07:22
☀️ Noon
13:33
🌇 Sunset
19:43
⏱️ Daylight
12h 20m
Wind Speed
20.9 km/h
Moderate wind
Sunshine
10.4 hrs
Direct Sun (Cloud-free)
Humidity
78%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Sintra
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 Sintra
Travel Comfort Index
Real-time tourism conditions
Weather Quality
☀️ Excellent
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
Rare minor tremors. Buildings are earthquake-resistant.
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Sintra on September 18 averages 22.5°C with a 13% precipitation probability. Wedding/Outdoor Event Score: 100/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Sintra Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Compare Other Cities
Same date (September 18) in other destinations
🌍 Explore the same date in different destinations around the world
📍 Is Sintra Worth Visiting on September 18?
Planning a trip to Sintra on September 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 22.5°C with a 13% historical precipitation risk.
✈️ Travel Logistics: Approximately 297 landing slots available daily during this period, indicating manageable crowd levels.
💉 Health Advisory: 6 vaccinations are recommended for Portugal, including COVID-19.
📊 Historical Extremes: The hottest September 18 recorded in the last 30 years saw temperatures hit 33°C in 2025, while the coldest dropped to 13.4°C in 2023.