January 21 is generally a great time to visit San Juan. While there is a slight chance of rain (19%), showers are usually brief. Expect comfortable 28°C weather. San Juan is currently in its most popular travel window, meaning vibrant crowds and premium pricing.
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Essential Travel Info for San Juan
Currency
USD
$ United States dollar
Language
English
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Driving
Right side
San Juan Weather Forecast for January 21
"Warm & Sunny. Expect average highs of 28°C. 19% chance of rain."
What to Wear in San Juan in January
Based on historical data for January 21, San Juan typically experiences temperatures between 21.9°C and 28°C. We recommend packing t-shirt, light clothing to stay comfortable. Trends suggest it will stay mostly dry (19% rain probability), but checking the forecast before heading out is always wise.
Complete Packing Guide
Weekly breakdown & essential items for San Juan
Smart Suitcase
- T-Shirt
- Light Clothing
Average High
28°C
Daytime Peak
Average Low
21.9°C
Nighttime Low
Feels Like
31.9°C
🔥 Feels warmer
Rain Chance
19%
Avg 1mm if it rains
Cloud Cover
37%
Light drizzle
Pressure
1017.1 hPa
Low volatility
San Juan Weather Conditions & UV Index
Weather Confidence
30-year variance analysis
Based on 10 years of data
🎯 This date historically delivers consistent weather 91% 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
🔴 133 min to burn
Type III-IV
🟡 200 min to burn
Type V-VI
🟢 333 min to burn
UV estimate based on latitude, season & cloud cover. Actual UV may vary.
Outdoor Comfort
How pleasant is it outside?
Dew Point
24°C
Humid/Sticky
Heat Index
31.9°C
Feels hotter
😐 Best outdoor time:
Morning hours (before 11 AM)
Marine Conditions
Marine Life
No special warnings. Enjoy the swim!
Swim Index
⚠️ Mixed Conditions
Travel & Logistics Insights
Local Calendar
Business Day
Standard hours in Puerto Rico
Flight Traffic
High
85/100 pressure index
Health Advisory
Required
2 vaccines • View Details →
Landing Slots
~183
Daily arrival options (inc. codeshare)
Sunrise, Sunset & Wind in San Juan
Daylight & Sun
Solar Elevation Cycle
🌅 Sunrise
07:00
☀️ Noon
12:36
🌇 Sunset
18:12
⏱️ Daylight
11h 11m
Wind Speed
19.3 km/h
Gentle breeze
Sunshine
10.4 hrs
Direct Sun (Cloud-free)
Humidity
79%
Humid / Damp
Travel Intelligence
Exclusive flight analytics & health data for San Juan
Smart Flight Estimator
Airport-to-Airport Logistics
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Travel Health & Safety in San Juan
Travel Comfort Index
Real-time tourism conditions
Weather Quality
☀️ Excellent
Tourist Crowds
🟢 Moderate
Price Level
💰💰 Moderate
Health & Wellbeing
Meteo-Health Forecast
Stable conditions. Low risk of headaches.
Weather unlikely to affect joint pain.
Moderate fish activity expected.
Air quality is excellent. Perfect for outdoor activities.
Regional Safety Profile
Seismic Activity
Moderate seismic activity. Occasional tremors possible.
Atlantic Hurricane Risk
Season: Jun - Nov
"According to 30YearWeather's analysis of 30 years of NASA satellite data, San Juan on January 21 averages 28°C with a 19% precipitation probability. Wedding/Outdoor Event Score: 95/100."
— Source: 30YearWeather.com|Data: NASA POWER (1991-2021)|View Methodology
San Juan Weather History (2010–2024)
Temperature History
Hall of Fame
Records from last 10 years
Better Alternatives Nearby
Consider these dates within ±7 days
January 14
27.8°C • 21% rain
Score
97
January 15
27.9°C • 19% rain
Score
97
January 16
27.9°C • 20% rain
Score
97
💡 Moving your event by a few days could significantly improve weather conditions
Compare Other Cities
Same date (January 21) in other destinations
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📍 Is San Juan Worth Visiting on January 21?
Planning a trip to San Juan on January 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 28°C with a 19% historical precipitation risk.
✈️ Travel Logistics: Approximately 183 landing slots available daily during this period, indicating manageable crowd levels.
💉 Health Advisory: 7 vaccinations are recommended for Puerto Rico, including COVID-19.
🌊 Coastal Conditions: Water temperature averages 27.1°C (tropical bath). Wave conditions are generally surfers only with heights around 1.38m.
📊 Historical Extremes: The hottest January 21 recorded in the last 30 years saw temperatures hit 30.5°C in 2016, while the coldest dropped to 19.3°C in 2017.