September 25 is generally a great time to visit Helsinki. While there is a slight chance of rain (19%), showers are usually brief. Expect comfortable 13°C weather. As it's peak season for Helsinki, we recommend booking your stay well in advance to secure the best rates.
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Essential Travel Info for Helsinki
Currency
EUR
€ Euro
Language
Finnish
+1 more
Driving
Right side
Connect
Much of Helsinki is blanketed withWi-Fi ...
Safety
Very High Safety
GPI: 1.439
Helsinki Weather Forecast for September 25
"Mild & Comfortable. Expect average highs of 13.3°C. 19% chance of rain."
What to Wear in Helsinki in September
Based on historical data for September 25, Helsinki typically experiences temperatures between 9.3°C and 13.3°C. We recommend packing light jacket, long pants to stay comfortable. Trends suggest it will stay mostly dry (19% rain probability), but checking the forecast before heading out is always wise.
Complete Packing Guide
Weekly breakdown & essential items for Helsinki
Smart Suitcase
- Light Jacket
- Long Pants
Average High
13.3°C
Daytime Peak
Average Low
9.3°C
Nighttime Low
Feels Like
12.6°C
🌤️ Feels accurate
Rain Chance
19%
Avg 0.8mm if it rains
Cloud Cover
64%
Overcast
Pressure
1015.6 hPa
High volatility
Helsinki Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
🎯 This date historically delivers consistent weather 98% of the time. Safe to plan outdoor activities with confidence.
Sun Exposure
UV Index & Safety Guide
Protection Needed
SPF 15 for extended outdoor time
Type I-II
🔴 50 min to burn
Type III-IV
🟡 75 min to burn
Type V-VI
🟢 125 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
10.1°C
Pleasant
Heat Stress
Low
No heat warning
😐 Best outdoor time:
Any time during daylight hours
Marine Conditions
Marine Life
No special warnings. Enjoy the swim!
Swim Index
❄️ Cold Water Hazard
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in Finland
Flight Traffic
High
98/100 pressure index
Health Advisory
Required
1 vaccine • View Details →
Landing Slots
~598
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Helsinki
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
06:11
☀️ Noon
12:13
🌇 Sunset
18:14
⏱️ Daylight
12h 2m
Wind Speed
20 km/h
Moderate wind
Sunshine
7.5 hrs
Direct Sun (Cloud-free)
Humidity
81%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Helsinki
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 Helsinki
Travel Comfort Index
Real-time tourism conditions
Weather Quality
☀️ Excellent
Tourist Crowds
🟡 Busy
Price Level
💰💰💰 Expensive
Health & Wellbeing
Meteo-Health Forecast
Rapid pressure changes detected. High risk for meteosensitive people.
Weather unlikely to affect joint pain.
Fish are active due to pressure changes.
Air quality is excellent. Perfect for outdoor activities.
Regional Safety Profile
Seismic Activity
Zero seismic activity detected in 30 years.
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Helsinki on September 25 averages 13.3°C with a 19% precipitation probability. Wedding/Outdoor Event Score: 88/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Helsinki Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Better Alternatives Nearby
Consider these dates within ±7 days
September 18
14.3°C • 23% rain
Score
93
September 19
14.3°C • 22% rain
Score
93
September 20
14.1°C • 22% rain
Score
92
💡 Moving your event by a few days could significantly improve weather conditions
Compare Other Cities
Same date (September 25) in other destinations
🌍 Explore the same date in different destinations around the world
📍 Is Helsinki Worth Visiting on September 25?
Planning a trip to Helsinki on September 25? Our historical weather analysis based on 30 years of NASA satellite data shows that this time of year offers a bracing seasonal atmosphere averaging 13.3°C with a 19% historical precipitation risk.
✈️ Travel Logistics: Approximately 598 landing slots available daily during this period, indicating peak tourist activity.
💉 Health Advisory: 8 vaccinations are recommended for Finland, including COVID-19.
🌊 Coastal Conditions: Water temperature averages 15.7°C (polar plunge). Wave conditions are generally fun waves with heights around 0.53m.
📊 Historical Extremes: The hottest September 25 recorded in the last 30 years saw temperatures hit 17.7°C in 2024, while the coldest dropped to 5.4°C in 2025.