April 21 is generally a great time to visit Boston. While there is a slight chance of rain (26%), showers are usually brief. Expect comfortable 15°C weather. Boston is currently in its most popular travel window, meaning vibrant crowds and premium pricing.
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Essential Travel Info for Boston
Currency
USD
$ United States dollar
Language
English
Driving
Right side
Connect
Greater Boston uses10-digit dialing. Th...
Safety
Moderate Safety
GPI: 2.44
Boston Weather Forecast for April 21
"Mild & Comfortable. Expect average highs of 15°C. 26% chance of snow."
What to Wear in Boston in April
Based on historical data for April 21, Boston typically experiences temperatures between 5.1°C and 15°C. We recommend packing light jacket, long pants to stay comfortable. With a 26% chance of rain, keeping a raincoat or umbrella handy is a smart move.
Complete Packing Guide
Weekly breakdown & essential items for Boston
Smart Suitcase
- Light Jacket
- Long Pants
Average High
15°C
Daytime Peak
Average Low
5.1°C
Nighttime Low
Feels Like
15°C
🌤️ Feels accurate
Snow Chance
26%
Avg 1.9mm if it snows
Snowfall
0.1 cm
~26% chance
Pressure
1015.9 hPa
Medium volatility
Boston 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 30 recommended
04:00 - 09:30
16:00 - 18:00
Type I-II
🔴 21 min to burn
Type III-IV
🟡 32 min to burn
Type V-VI
🟢 53 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
9.4°C
Dry air
Heat Stress
Low
No heat warning
🙂 Best outdoor time:
Any time during daylight hours
Marine Conditions
Marine Life
No special warnings. Enjoy the swim!
Swim Index
❄️ Cold Water Hazard
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in United States
Flight Traffic
High
88/100 pressure index
Health Advisory
Healthy
Routine only • View Details →
Landing Slots
~596
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Boston
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
04:55
☀️ Noon
11:44
🌇 Sunset
18:32
⏱️ Daylight
13h 37m
Wind Speed
20.6 km/h
Moderate wind
Sunshine
9.1 hrs
Direct Sun (Cloud-free)
Humidity
69%
Slightly humid
Travel Intelligence
Exclusive flight analytics & health data for Boston
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 Boston
Travel Comfort Index
Real-time tourism conditions
Weather Quality
⛅ Good
Tourist Crowds
🟡 Busy
Price Level
💰💰 Moderate
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.
Atlantic Hurricane Risk
Season: Jun - Nov
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Boston on April 21 averages 15°C with a 26% precipitation probability. Wedding/Outdoor Event Score: 79/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
Boston Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Better Alternatives Nearby
Consider these dates within ±7 days
April 20
14.8°C • 21% rain
Score
89
April 28
14.8°C • 26% rain
Score
89
April 19
14.6°C • 19% rain
Score
88
💡 Moving your event by a few days could significantly improve weather conditions
Compare Other Cities
Same date (April 21) in other destinations
🌍 Explore the same date in different destinations around the world
📍 Is Boston Worth Visiting on April 21?
Planning a trip to Boston on April 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 15°C with a 26% historical precipitation risk.
✈️ Travel Logistics: Approximately 596 landing slots available daily during this period, indicating peak tourist activity.
🌊 Coastal Conditions: Water temperature averages 8.6°C (polar plunge). Wave conditions are generally fun waves with heights around 0.51m.
📊 Historical Extremes: The hottest April 21 recorded in the last 30 years saw temperatures hit 22.2°C in 2016, while the coldest dropped to 0.7°C in 2020.