September 21 is statistically one of the best days of the year in Yellowknife. With minimal rain risk (12%) and pleasant highs of 11°C, it's ideal for outdoor adventures. It's a lively time to explore Yellowknife, with most attractions operating at full capacity.
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Essential Travel Info for Yellowknife
Currency
CAD
$ Canadian dollar
Language
English
+1 more
Driving
Right side
Safety
Very High Safety
GPI: 1.389
Yellowknife Weather Forecast for September 21
"Mild & Comfortable. Expect average highs of 11.1°C. 12% chance of snow."
What to Wear in Yellowknife in September
Based on historical data for September 21, Yellowknife typically experiences temperatures between 5.7°C and 11.1°C. We recommend packing heavy coat, scarf, gloves to stay comfortable. Trends suggest it will stay mostly dry (12% rain probability), but checking the forecast before heading out is always wise.
Complete Packing Guide
Weekly breakdown & essential items for Yellowknife
Smart Suitcase
- Heavy Coat
- Scarf
- Gloves
Average High
11.1°C
Daytime Peak
Average Low
5.7°C
Nighttime Low
Feels Like
9.6°C
❄️ Minor difference
Snow Chance
12%
Avg 0.5mm if it snows
Snowfall
0.1 cm
~12% chance
Pressure
1008.2 hPa
High volatility
Yellowknife Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
✓ This date historically delivers consistent weather 78% 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
🔴 53 min to burn
Type III-IV
🟡 80 min to burn
Type V-VI
🟢 133 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
7.4°C
Dry air
Heat Stress
Low
No heat warning
😐 Best outdoor time:
Any time during daylight hours
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in Canada
Flight Traffic
Busy
68/100 pressure index
Health Advisory
Required
1 vaccine • View Details →
Landing Slots
~15
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Yellowknife
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
06:19
☀️ Noon
12:31
🌇 Sunset
18:44
⏱️ Daylight
12h 24m
Wind Speed
19.5 km/h
Gentle breeze
Sunshine
7.8 hrs
Direct Sun (Cloud-free)
Humidity
78%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Yellowknife
Smart Flight Estimator
Airport-to-Airport Logistics
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Add your home location in settings to see airport details.
Travel Health & Safety in Yellowknife
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.
Mild discomfort possible for arthritic conditions.
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, Yellowknife on September 21 averages 11.1°C with a 12% precipitation probability. Wedding/Outdoor Event Score: 80/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Yellowknife Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Better Alternatives Nearby
Consider these dates within ±7 days
September 14
12.1°C • 14% rain
Score
85
September 15
11.9°C • 13% rain
Score
84
September 16
11.5°C • 13% rain
Score
81
💡 Moving your event by a few days could significantly improve weather conditions
Compare Other Cities
Same date (September 21) in other destinations
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Rome
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United Kingdom
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🌍 Explore the same date in different destinations around the world
📍 Is Yellowknife Worth Visiting on September 21?
Planning a trip to Yellowknife on September 21? Our historical weather analysis based on 30 years of NASA satellite data shows that this time of year offers a bracing seasonal atmosphere averaging 11.1°C with a 12% historical precipitation risk.
✈️ Travel Logistics: Approximately 15 landing slots available daily during this period, indicating manageable crowd levels.
💉 Health Advisory: 6 vaccinations are recommended for Canada, including COVID-19.
📊 Historical Extremes: The hottest September 21 recorded in the last 30 years saw temperatures hit 17.7°C in 2025, while the coldest dropped to -2.3°C in 2018.