September 21 is generally a great time to visit Interlaken. While there is a slight chance of rain (32%), showers are usually brief. Expect comfortable 19°C weather. Interlaken is currently in its most popular travel window, meaning vibrant crowds and premium pricing. Note: September 21 is Federal Day of Thanksgiving in Interlaken, so expect special events, closures, and festive atmosphere.
View the full calendar
Essential Travel Info for Interlaken
Currency
CHF
Fr. Swiss franc
Language
French
+3 more
Driving
Right side
Connect
As of March 2022 formobile devices, Inte...
Safety
Very High Safety
GPI: 1.357
Interlaken Weather Forecast for September 21
"Mild & Comfortable. Expect average highs of 18.6°C. 32% chance of rain."
What to Wear in Interlaken in September
Based on historical data for September 21, Interlaken typically experiences temperatures between 10.2°C and 18.6°C. We recommend packing light jacket, long pants, umbrella to stay comfortable. With a 32% chance of rain, keeping a raincoat or umbrella handy is a smart move.
Complete Packing Guide
Weekly breakdown & essential items for Interlaken
Smart Suitcase
- Light Jacket
- Long Pants
- Umbrella
Average High
18.6°C
Daytime Peak
Average Low
10.2°C
Nighttime Low
Feels Like
18.6°C
🌤️ Feels accurate
Rain Chance
32%
Avg 2mm if it rains
Cloud Cover
66%
Overcast
Pressure
1018.1 hPa
Medium volatility
Interlaken Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
🎯 This date historically delivers consistent weather 83% 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
🔴 35 min to burn
Type III-IV
🟡 53 min to burn
Type V-VI
🟢 88 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
15.7°C
Pleasant
Heat Stress
Low
No heat warning
🙂 Best outdoor time:
Any time during daylight hours
Travel & Logistics Insights
Local Calendar
Holiday
Federal Day of Thanksgiving
Flight Traffic
High
97/100 pressure index
Health Advisory
Required
1 vaccine • View Details →
Landing Slots
~519
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Interlaken
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
06:14
☀️ Noon
12:23
🌇 Sunset
18:31
⏱️ Daylight
12h 16m
Wind Speed
7.9 km/h
Light breeze
Sunshine
9.2 hrs
Direct Sun (Cloud-free)
Humidity
83%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Interlaken
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 Interlaken
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 excellent. Perfect for outdoor activities.
Regional Safety Profile
Seismic Activity
Rare minor tremors. Buildings are earthquake-resistant.
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Interlaken on September 21 averages 18.6°C with a 32% precipitation probability. Wedding/Outdoor Event Score: 90/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Interlaken Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Better Alternatives Nearby
Consider these dates within ±7 days
💡 Moving your event by a few days could significantly improve weather conditions
Compare Other Cities
Same date (September 21) in other destinations
Prague
Czech Republic
Paris
France
Rome
Italy
London
United Kingdom
Amsterdam
Netherlands
🌍 Explore the same date in different destinations around the world
📍 Is Interlaken Worth Visiting on September 21?
Planning a trip to Interlaken on September 21? 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 18.6°C with a 32% historical precipitation risk.
🎉 Local Event: The date coincides with Federal Day of Thanksgiving, which may influence local business hours and event availability.
✈️ Travel Logistics: Approximately 519 landing slots available daily during this period, indicating peak tourist activity.
💉 Health Advisory: 7 vaccinations are recommended for Switzerland, including COVID-19.
📊 Historical Extremes: The hottest September 21 recorded in the last 30 years saw temperatures hit 27.3°C in 2018, while the coldest dropped to 7.8°C in 2022.