The month in detail
What to expect in September
Autumn marks the end of peak season in San Juan. Temperatures drop (31°C) and rain returns (42% of days). Expect rain on 42% of days — a light raincoat in the bag is recommended.
September ranks 12 out of 12 months in San Juan. Compared to August: 9 pts more rainy days, −0.8h of sun per day.
This month's conditions
What it's like in September
UV index
8 · very high
protection essential
Feels like
very humid
24°
Sea
30°C
warm, ideal
Daylight
12.1h of daylight
Air quality
excellent
AQI 16
Compare
Is September the right month?
The best month in San Juan is March (8.8/10), 3.6 pts higher than September.
Book
Plan your trip
Hotels at their lowest outside peak season, highest on comfortable months. Shoulder seasons offer a good price/climate compromise.
Stay
Hotels & rentals · San Juan
Expedia →
Activities
Tours, tickets, experiences
See ↓
Flights
Multi-airline comparator
Kiwi →
🎟️ Activities & tours · San Juan
GetYourGuide selection · free cancellation
Practical info
What you need to know before you go
Three angles: the country (language, currency, safety, budget), the year-round climate, and the specifics of a tropical stay.
Country · Puerto Rico
🗣️LanguageSpanish
💶CurrencyUS Dollar ($)
🚗DrivingRight-hand
🛡️Safety ⓘVery safe · 1/5
💰Cost of living ⓘExpensive · 4/5
🌡️ Climate
🌍Climate typeTropical
📈Climate trend ⓘStable
🔥Hottest monthJune · 31°C
❄️Coolest monthJanuary · 28°C
🌧️Rainiest month ⓘSeptember · 42%
🏝️ Tropical stay
🌞Dry season ⓘMay → Sep
🌧️Wet season ⓘDec → Mar
🌀Cyclones ⓘSeason Nov-Apr
Explore
Other destinations in September
If September doesn't convince you for this destination, compare with others.
Similar climate
Puerto RicoPuerto Rico
AntiguaAntigua and Barbuda
DominicaDominica
Saint MartinSaint Martin
Cayman IslandsCayman Islands
Location
Where is San Juan ?
Global position + regional geographic context.
🌍 World
🔍 Geographic context
Puerto RicoTropical climate with a 8.8 → 5.2 gap between best and worst month. 10 years of ERA5 data to choose by project.
18.47°N · 66.11°W
Questions
Frequently asked questions
What is the best time to visit San Juan?
March is the best month with 28.0°C highs, 22.0°C lows, 9.1h of sunshine and 25.0% rainy days. The months of March & January offer comparable conditions.
How many hours of sunshine does San Juan get in March?
San Juan averages 9.1 sunshine hours per day in March. It is the sunniest month with a climate score of 8.3/10.
What is the rainiest month in San Juan?
September is the most unfavourable month with September has the lowest climate score of the year and the lowest climate score of the year.
What are the temperatures at night in San Juan in March?
In March, overnight lows reach 22.0°C, while afternoon highs average 28.0°C.
Is San Juan good in winter?
In winter (December-February), San Juan scores 8.1/10 on average — Decent period conditions for cultural visits.. The best month overall remains March with a score of 8.3/10.
When should you avoid San Juan?
September is the most difficult month to visit San Juan, with September has the lowest climate score of the year. Climate conditions are at their lowest of the year during this period.
Can you swim in San Juan in September?
In September, the sea averages 30°C in San Juan: warm, ideal. Ideal conditions for swimming and snorkeling.
Do you need sun protection in San Juan in September?
The average UV index reaches 8 in September in San Juan (very high), with about 12.1h of daylight. Protection essential.