Weather in San Juan 🇵🇷
Monthly weather averages & travel planning
December
Avg Temp
28°C
Rain Days
13 days
Sun Hours
11 hrs
Humidity
78%
North America › 🇵🇷 Puerto Rico › San Juan
Updated: March 2026
Is December a Good Time to Visit San Juan?
6/10
Good
December is a good time to visit San Juan (6/10). With 11 daily sunshine hours and only 13 rain days, this month delivers genuinely reliable outdoor conditions, ranking it 11th sunniest of the year in San Juan. Culture-focused travellers and those who prefer lighter crowds will find December a practical choice, with prices running lower than peak April without sacrificing all the good weather. November offers a similar profile at lower hotel rates if dates are flexible. The main practical note: San Juan's popular sites are busiest between 10am and 3pm regardless of season. Arriving at opening time or after 4pm makes a significant difference to the experience. Planning tips: accommodation is generally available without long lead times, and flight prices are typically lower than peak season. Flexible travellers will find the best deals by booking 2-4 weeks ahead. Mid-week arrivals consistently unlock lower hotel rates than weekend check-ins.
vs November:29°C avg high
San Juan's December weather is shaped by atmospheric forces that make the data more than just numbers. The 28°C average high reflects the dominance of a stable subtropical air mass, which suppresses cloud formation and concentrates solar energy at the surface. As a result, 11 daily sunshine hours are recorded on average, and rainfall of 49mm is distributed across approximately 13 days because precipitation events tend to be frequent but short-lived.
28°C
82°F
Avg High
22°C
72°F
Avg Low
13 days
49 mm total
Rain Days
11h
per day avg
Sunshine
78%
Humid
Humidity
Temperature in San Juan in December
The 6°C day-night temperature range is typical for continental climates: a light jacket in the morning that you shed by midday and need again after sunset. At 78% humidity, the 28°C daytime high feels 2-4°C warmer in practice: quick-dry fabrics and shade-seeking between noon and 3pm are the sensible response. The UV index of 3 is low, meaning sun exposure is minimal concern and sunscreen is largely optional. Wind averages 20 km/h, light enough to be refreshing on warm days but noticeable in open coastal areas or elevated viewpoints. In Fahrenheit: 82°F average high, 72°F overnight low. Data sourced from Open-Meteo ERA5 climate reanalysis (1991–2020 normals).
Temperature Trends
High
Low
Rainfall (mm)
0-20 mm21-50 mm51-100 mm100+ mm
What to Wear in San Juan in December
Morning22°CBefore the day warms up
Afternoon28°CPeak daytime temperature
Evening25°CAfter sunset cools down
Packing for San Juan in December means dressing for 28°C days and 22°C evenings. A light cotton tee with a casual overshirt works well at 28°C, the overshirt doubles as a layer for air-conditioned venues. Evening temperatures settle at 22°C, a modest 6°C drop that a light cardigan or denim jacket covers. Comfortable walking trainers are the versatile choice for both outdoor sightseeing and indoor venues. With 13 rain days expected, a compact travel umbrella is worth the bag space. A waterproof jacket is better than an umbrella if you plan full-day outdoor routes. At 78% average humidity, quick-dry synthetic or bamboo fabrics dry overnight and stay comfortable longer than cotton.
Local tip: Layers are more practical than a single heavy garment in San Juan. The day-to-evening temperature shift rewards packing a versatile mid-layer you can add or remove as conditions change.
Events in San Juan in December
December has no major festivals or public holidays in San Juan, which is one of its practical advantages for independent travellers. Attractions run at lower capacity than during peak event periods, queues are shorter, and accommodation is easier to find without needing to book many months in advance. Local restaurants, markets, and transport operate at a relaxed pace, making this an ideal time for visitors who prefer a more authentic, unhurried experience of everyday city life rather than large crowds drawn in by a single major headline event.
What to Pack for San Juan in December
Based on 28°C average highs and 13 rainy days
- Light layers for morning and evening
- Breathable T-shirts and comfortable trousers
- UV-protective sunglasses
- Quick-dry travel towel
- Anti-chafe balm for long walking days
- Moisture-wicking synthetic fabrics for active days
- Compact folding umbrella
- Waterproof outer layer or packable rain jacket
- Quick-dry clothing that recovers fast after a shower
- SPF 30+ sunscreen
- Comfortable walking shoes (a second pair lets the first air out overnight)
- Universal travel adapter
- Small day pack for city exploration
- Reusable water bottle
Best Activities in San Juan in December
- Explore outdoor markets and street food stallsMid-morning (10am-12pm)At 28°C, the temperature is ideal for extended walking without overheating
- Guided walking tour of the historic centreMorning or late afternoonComfortable temperatures allow several hours on foot without fatigue
- Visit rooftop viewpoints and observation decksGolden hour (1 hour before sunset)Warm clear evenings provide exceptional visibility for panoramic photography
- Day trip to the surrounding countryside or coastFull day (depart by 8am)December is reliably dry enough for rural day trips without weather risk
- Spend a morning in the national or city art museumOpens at 10am; arrive earlyWith 13 rain days expected, having a full-day indoor plan is practical insurance
- Cooking class focused on regional cuisineHalf-day sessions run 10am-1pm or 3-6pmIndoor activity that fills a rainy half-day with genuine cultural content
- Visit covered historical sites: cathedral, palace, or bazaarAny time; most crowded middayRoofed monuments and covered markets provide exploration without weather exposure
- Visit the main botanical garden or city park at seasonal peakYear-round; best light in morningDecember brings distinct seasonal changes to public green spaces worth exploring
- Seek out chilled local specialities: cold-brew tea, ice desserts, or chilled seafood at street-level stallsAny time; most atmospheric in evening marketsHot-weather street food culture peaks in December, with vendors setting up specifically for warm evenings
Why is San Juan warm in December?
In December, San Juan sits in the dry season corridor, as the ITCZ shifts away from the region and trade winds bring drier, more stable air. This produces reliably sunny days reaching 28°C, with lower humidity than the wet months. Overnight lows of 22°C offer a pleasant reprieve from the midday heat. Climate data: Open-Meteo ERA5 (1991–2020).
Sunshine Hours
The average number of hours per day with direct sunlight. Calculated from satellite measurements. Days with more than 7 hours of sunshine are ideal for outdoor activities. Under 3 hours means overcast conditions dominate.
UV Index
A scale from 0-11+ measuring ultraviolet radiation intensity. UV 0-2: Minimal risk. UV 3-5: Moderate, wear sunscreen. UV 6-7: High, hat and SPF 30+ essential. UV 8-10: Very High, limit midday exposure. UV 11+: Extreme, seek shade between 10am-4pm.
Rain Days
A rain day is counted when precipitation exceeds 0.1mm. This threshold captures even light drizzle. Unlike total rainfall in mm, rain days tells you how often you might need an umbrella, which is useful for planning outdoor activities.
Humidity
Relative humidity as a percentage. Below 40%: Dry, skin and throat may feel parched. 40-60%: Comfortable, ideal for most people. 60-80%: Sticky, light breathable fabrics recommended. Above 80%: Muggy, heat feels more intense; quick-dry clothing is essential.
Frequently Asked Questions
San Juan in December
In December, San Juan experiences average highs of 28°C (82°F) and lows of 22°C (72°F). Expect around 13 rainy days and 11 hours of sunshine per day, with humidity averaging 78%. The 6°C gap between daytime and overnight temperatures is worth planning around: light layers work for most visitors during the day, but an overshirt or cardigan handles the cooler evenings. UV exposure is moderate at index 3.
San Juan typically sees 13 rainy days in December, with total precipitation of around 49mm. Rain is moderate and manageable. Showers tend to pass quickly, and a light rain layer or foldable umbrella is sufficient protection for most days. For context, the driest month in San Juan typically sees 4-6 fewer rain days than December.
Pack light layers, a light jacket for evenings, comfortable walking shoes, and sunscreen for San Juan in December. Daytime temperatures of 28°C are pleasant, but the evening drop to 22°C means a jacket is essential if you plan to be out after dark. With 13 rainy days, bring a compact umbrella or waterproof jacket for unexpected showers. Comfortable walking shoes are a priority given the amount of ground most visitors cover.
December is a reasonable time to visit San Juan. Expect 13 rainy days, so pack a light rain layer for flexibility. Average temperatures of 28°C make outdoor exploration comfortable during the dry periods. With 11 daily sunshine hours, there are reliable windows of good weather to plan outdoor activities around, even if the month is not the driest on the calendar.
The average high temperature in San Juan in December is 28°C (82°F), and the average low is 22°C (72°F). The mean daily temperature is approximately 25°C (77°F). The day-to-night range of 6°C is moderate, meaning a single light jacket covers most situations. These are 30-year climate normals based on the 1991 to 2020 reference period; individual years will vary, particularly in transitional months like spring and autumn.
The best month to visit San Juan is generally January. January offers the most sunshine at 11 hours per day and only 11 rainy days. Average temperatures reach 28°C, making it comfortable for sightseeing, outdoor dining, and exploring the city. If your travel dates are flexible, planning your trip around January gives you the best chance of dry, bright weather.
December is shoulder or low season in San Juan, meaning fewer tourists and generally lower prices than peak months. With 11 sunshine hours and 13 rainy days, the weather is less of a draw for mass tourism. This is an advantage for travellers who prefer a quieter, more relaxed experience with shorter queues and easier accommodation availability.
In December, San Juan suits a range of activities thanks to mild temperatures around 28°C. Mix of indoor and outdoor activities works well given the moderate chance of rain. Top options include exploring historic neighbourhoods, visiting museums and galleries, local food markets, and day trips to surrounding areas. With 11 hours of sunshine, parks and waterfront walks are particularly enjoyable.
December ranks 11th sunniest of the year in San Juan, with an average 11 daily sunshine hours. The driest months are February, March, and January. June is the hottest month (31°C avg high); January is the coolest (28°C). From here, temperatures fall 0°C into January. Compared to last month (November: 29°C high, 19 rain days), December is cooler and drier. December is one of the least sunny months, but that often means lower prices and fewer fellow tourists.
Year-Round Climate
| Month | High | Low | Rain Days | Sun | Details |
|---|---|---|---|---|---|
| January | 28°C | 22°C | 11 | 11h | View |
| February | 29°C | 21°C | 9 | 11h | View |
| March | 29°C | 22°C | 9 | 11h | View |
| April | 30°C | 22°C | 12 | 12h | View |
| May | 30°C | 23°C | 17 | 12h | View |
| June | 31°C | 24°C | 14 | 12h | View |
| July | 31°C | 25°C | 17 | 12h | View |
| August | 31°C | 25°C | 19 | 12h | View |
| September | 31°C | 25°C | 21 | 11h | View |
| October | 30°C | 24°C | 21 | 11h | View |
| November | 29°C | 23°C | 19 | 10h | View |
| December | 28°C | 22°C | 13 | 11h | View |
January
11 rain days, 11h sun
28°22°
February
9 rain days, 11h sun
29°21°
March
9 rain days, 11h sun
29°22°
April
12 rain days, 12h sun
30°22°
May
17 rain days, 12h sun
30°23°
June
14 rain days, 12h sun
31°24°
July
17 rain days, 12h sun
31°25°
August
19 rain days, 12h sun
31°25°
September
21 rain days, 11h sun
31°25°
October
21 rain days, 11h sun
30°24°
November
19 rain days, 10h sun
29°23°
December
13 rain days, 11h sun
28°22°
Other Months in San Juan
Plan Your Trip to San Juan
Data Sources for San Juan
Climate normals represent 30-year averages (1991-2020). Individual years may vary.