August 21 is statistically one of the best days of the year in Rio de Janeiro. With minimal rain risk (14%) and pleasant highs of 27°C, it's ideal for outdoor adventures. It's a lively time to explore Rio de Janeiro, with most attractions operating at full capacity.
View the full calendar
Essential Travel Info for Rio de Janeiro
Currency
BRL
R$ Brazilian real
Language
Portuguese
Driving
Right side
Safety
Moderate Safety
GPI: 2.465
Rio de Janeiro Weather Forecast for August 21
"Warm & Sunny. Expect average highs of 27°C. 14% chance of rain."
What to Wear in Rio de Janeiro in August
Based on historical data for August 21, Rio de Janeiro typically experiences temperatures between 17.1°C and 27°C. We recommend packing t-shirt, light clothing to stay comfortable. Trends suggest it will stay mostly dry (14% rain probability), but checking the forecast before heading out is always wise.
Complete Packing Guide
Weekly breakdown & essential items for Rio de Janeiro
Smart Suitcase
- T-Shirt
- Light Clothing
Average High
27°C
Daytime Peak
Average Low
17.1°C
Nighttime Low
Feels Like
29.2°C
🔥 Feels warmer
Rain Chance
14%
Avg 0.6mm if it rains
Cloud Cover
40%
Overcast
Pressure
1019 hPa
Medium volatility
Rio de Janeiro Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
✓ This date historically delivers consistent weather 77% 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
🔴 40 min to burn
Type III-IV
🟡 60 min to burn
Type V-VI
🟢 100 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
22°C
Humid/Sticky
Heat Index
29.2°C
Feels hotter
😐 Best outdoor time:
Morning hours (before 11 AM)
Marine Conditions
Marine Life
No special warnings. Enjoy the swim!
Swim Index
✅ Excellent Swimming Conditions
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in Brazil
Flight Traffic
Busy
63/100 pressure index
Health Advisory
Required
2 vaccines • View Details →
Landing Slots
~157
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Rio de Janeiro
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
06:14
☀️ Noon
11:57
🌇 Sunset
17:40
⏱️ Daylight
11h 25m
Wind Speed
16.2 km/h
Gentle breeze
Sunshine
8.8 hrs
Direct Sun (Cloud-free)
Humidity
74%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Rio de Janeiro
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 Rio de Janeiro
Travel Comfort Index
Real-time tourism conditions
Weather Quality
☀️ Excellent
Tourist Crowds
🔴 Very 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
Zero seismic activity detected in 30 years.
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Rio de Janeiro on August 21 averages 27°C with a 14% precipitation probability. Wedding/Outdoor Event Score: 100/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Rio de Janeiro Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Compare Other Cities
Same date (August 21) in other destinations
🌍 Explore the same date in different destinations around the world
📍 Is Rio de Janeiro Worth Visiting on August 21?
Planning a trip to Rio de Janeiro on August 21? Our historical weather analysis based on 30 years of NASA satellite data shows that this time of year typically offers vibrant summer conditions averaging 27°C with a 14% historical precipitation risk.
✈️ Travel Logistics: Approximately 157 landing slots available daily during this period, indicating manageable crowd levels.
💉 Health Advisory: 9 vaccinations are recommended for Brazil, including COVID-19.
🌊 Coastal Conditions: Water temperature averages 22.3°C (swimming pool). Wave conditions are generally fun waves with heights around 0.88m.
📊 Historical Extremes: The hottest August 21 recorded in the last 30 years saw temperatures hit 30.4°C in 2025, while the coldest dropped to 13.7°C in 2022.