May 21 is generally a great time to visit Ottawa. While there is a slight chance of rain (25%), showers are usually brief. Expect comfortable 20°C weather. Ottawa is seeing high visitor numbers, so iconic spots may be busier than usual.
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Essential Travel Info for Ottawa
Currency
CAD
$ Canadian dollar
Language
English
+1 more
Driving
Right side
Connect
The area codes for Ottawa are613and the ...
Safety
Very High Safety
GPI: 1.389
Ottawa Weather Forecast for May 21
"Mild & Comfortable. Expect average highs of 19.7°C. 25% chance of rain."
What to Wear in Ottawa in May
Based on historical data for May 21, Ottawa typically experiences temperatures between 8.8°C and 19.7°C. We recommend packing light jacket, long pants to stay comfortable. Trends suggest it will stay mostly dry (25% rain probability), but checking the forecast before heading out is always wise.
Complete Packing Guide
Weekly breakdown & essential items for Ottawa
Smart Suitcase
- Light Jacket
- Long Pants
Average High
19.7°C
Daytime Peak
Average Low
8.8°C
Nighttime Low
Feels Like
19.7°C
🌤️ Feels accurate
Rain Chance
25%
Avg 1.6mm if it rains
Cloud Cover
65%
Overcast
Pressure
1015.4 hPa
Medium volatility
Ottawa 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 30 recommended
04:00 - 10:00
16:00 - 19:00
Type I-II
🔴 19 min to burn
Type III-IV
🟡 29 min to burn
Type V-VI
🟢 48 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
13.4°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 Canada
Flight Traffic
Busy
65/100 pressure index
Health Advisory
Required
1 vaccine • View Details →
Landing Slots
~115
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Ottawa
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
04:27
☀️ Noon
12:00
🌇 Sunset
19:33
⏱️ Daylight
15h 6m
Wind Speed
15.9 km/h
Gentle breeze
Sunshine
9.7 hrs
Direct Sun (Cloud-free)
Humidity
67%
Slightly humid
Travel Intelligence
Exclusive flight analytics & health data for Ottawa
Smart Flight Estimator
Airport-to-Airport Logistics
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Travel Health & Safety in Ottawa
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, Ottawa on May 21 averages 19.7°C with a 25% precipitation probability. Wedding/Outdoor Event Score: 93/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Ottawa Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Better Alternatives Nearby
Consider these dates within ±7 days
May 26
20.9°C • 25% rain
Score
97
May 25
20.5°C • 26% rain
Score
96
May 27
21.2°C • 25% rain
Score
96
💡 Moving your event by a few days could significantly improve weather conditions
Compare Other Cities
Same date (May 21) in other destinations
🌍 Explore the same date in different destinations around the world
📍 Is Ottawa Worth Visiting on May 21?
Planning a trip to Ottawa on May 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 19.7°C with a 25% historical precipitation risk.
✈️ Travel Logistics: Approximately 115 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 May 21 recorded in the last 30 years saw temperatures hit 29.9°C in 2021, while the coldest dropped to 6.7°C in 2017.