September 21 is statistically one of the best days of the year in Warsaw. With minimal rain risk (13%) and pleasant highs of 18°C, it's ideal for outdoor adventures. As it's peak season for Warsaw, we recommend booking your stay well in advance to secure the best rates.
View the full calendar
Essential Travel Info for Warsaw
Currency
PLN
zł Polish złoty
Language
Polish
Driving
Right side
Connect
Free wi-fi is widespread in Warsaw. Muni...
Safety
High Safety
GPI: 1.552
Warsaw Weather Forecast for September 21
"Mild & Comfortable. Expect average highs of 17.9°C. 13% chance of rain."
What to Wear in Warsaw in September
Based on historical data for September 21, Warsaw typically experiences temperatures between 9.5°C and 17.9°C. We recommend packing light jacket, long pants 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 Warsaw
Smart Suitcase
- Light Jacket
- Long Pants
Average High
17.9°C
Daytime Peak
Average Low
9.5°C
Nighttime Low
Feels Like
17.9°C
🌤️ Feels accurate
Rain Chance
13%
Avg 0.6mm if it rains
Cloud Cover
56%
Overcast
Pressure
1018.1 hPa
Medium volatility
Warsaw Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
✓ Weather is generally predictable, but pack for minor variations. A light backup layer is recommended.
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
13.2°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 Poland
Flight Traffic
High
97/100 pressure index
Health Advisory
Required
1 vaccine • View Details →
Landing Slots
~285
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Warsaw
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
05:20
☀️ Noon
11:30
🌇 Sunset
17:40
⏱️ Daylight
12h 19m
Wind Speed
15.5 km/h
Gentle breeze
Sunshine
8.0 hrs
Direct Sun (Cloud-free)
Humidity
74%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Warsaw
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 Warsaw
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 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, Warsaw on September 21 averages 17.9°C with a 13% precipitation probability. Wedding/Outdoor Event Score: 100/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Warsaw Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
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 Warsaw Worth Visiting on September 21?
Planning a trip to Warsaw 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 17.9°C with a 13% historical precipitation risk.
✈️ Travel Logistics: Approximately 285 landing slots available daily during this period, indicating manageable crowd levels.
💉 Health Advisory: 8 vaccinations are recommended for Poland, including COVID-19.
📊 Historical Extremes: The hottest September 21 recorded in the last 30 years saw temperatures hit 28.5°C in 2025, while the coldest dropped to 4.9°C in 2021.