October 21 is generally a great time to visit Boston. While there is a slight chance of rain (18%), showers are usually brief. Expect comfortable 16°C weather. Expect a bustling atmosphere in Boston right now—this is when the city truly comes alive with visitors.
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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 October 21
"Mild & Comfortable. Expect average highs of 16.4°C. 18% chance of rain."
What to Wear in Boston in October
Based on historical data for October 21, Boston typically experiences temperatures between 7.8°C and 16.4°C. We recommend packing light jacket, long pants to stay comfortable. Trends suggest it will stay mostly dry (18% rain probability), but checking the forecast before heading out is always wise.
Complete Packing Guide
Weekly breakdown & essential items for Boston
Smart Suitcase
- Light Jacket
- Long Pants
Average High
16.4°C
Daytime Peak
Average Low
7.8°C
Nighttime Low
Feels Like
16.4°C
🌤️ Feels accurate
Rain Chance
18%
Avg 1.4mm if it rains
Cloud Cover
50%
Overcast
Pressure
1015.6 hPa
High volatility
Boston 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
🔴 57 min to burn
Type III-IV
🟡 86 min to burn
Type V-VI
🟢 143 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
11.8°C
Pleasant
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
94/100 pressure index
Health Advisory
Healthy
Routine only • View Details →
Landing Slots
~635
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in Boston
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
06:05
☀️ Noon
11:30
🌇 Sunset
16:54
⏱️ Daylight
10h 49m
Wind Speed
20 km/h
Moderate wind
Sunshine
7.6 hrs
Direct Sun (Cloud-free)
Humidity
74%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for Boston
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 Boston
Travel Comfort Index
Real-time tourism conditions
Weather Quality
☀️ Excellent
Tourist Crowds
🟡 Busy
Price Level
💰💰 Moderate
Health & Wellbeing
Meteo-Health Forecast
Rapid pressure changes detected. High risk for meteosensitive people.
Weather unlikely to affect joint pain.
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.
Atlantic Hurricane Risk
Season: Jun - Nov
"According to 30YearWeather's analysis of 30 years of NASA satellite data, Boston on October 21 averages 16.4°C with a 18% precipitation probability. Wedding/Outdoor Event Score: 86/100."
— 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
October 26
14.8°C • 20% rain
Score
93
October 14
17°C • 27% rain
Score
89
October 27
14.3°C • 25% rain
Score
89
💡 Moving your event by a few days could significantly improve weather conditions
Compare Other Cities
Same date (October 21) in other destinations
🌍 Explore the same date in different destinations around the world
📍 Is Boston Worth Visiting on October 21?
Planning a trip to Boston on October 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 16.4°C with a 18% historical precipitation risk.
✈️ Travel Logistics: Approximately 635 landing slots available daily during this period, indicating peak tourist activity.
🌊 Coastal Conditions: Water temperature averages 14°C (polar plunge). Wave conditions are generally fun waves with heights around 0.56m.
📊 Historical Extremes: The hottest October 21 recorded in the last 30 years saw temperatures hit 25.1°C in 2017, while the coldest dropped to 1°C in 2018.