Middle of the wetter season · Weather & things to do
Old San Juan in September
The year's rain peaks now, with about 6.4 in (162 mm) falling in Old San Juan, alongside highs near 86°F (30°C) and lows of 80°F (27°C).
With a comfort score of 53/100 (12th of 12), it's one of the toughest months, held back mainly by cloud cover.
- Avg high
- 86°F (30°C)
- Avg low
- 80°F (27°C)
- Rain
- 6.4 in (162 mm)
- Humidity
- 79%
- Cloud cover
- 68%
- Daylight
- ~12 h 06 min
- Comfort score
- 53/100 · Fair
What September feels like
Heat sets the pace, with highs around 86°F (30°C). Get out early and keep the hottest hours for somewhere cool.
Nights stay warm too, with lows averaging 80°F (27°C).
With 79% average humidity, it feels muggy.
Expect regular rain: about 6.4 in (162 mm) falls in the month.
Plan around September
September is one of the lower-scoring months here; the best are December – March.
- Start of the wettest three-month stretch (September – November), which brings about 18.1 in (460 mm) in total.
- Comfort slips from 57/100 in August to 53/100.
- Our Old San Juan & Ponce route is planned for Dec – mid-Jan, a window set by the holiday season rather than the weather — September falls outside it.
What to pack for September
- Light, breathable clotheshighs average 86°F
- Sunscreen, sunglasses and a hatstrong sun this month
- Refillable water bottleeasy to dehydrate in the heat
- Quick-dry fabrics79% average humidity
- Rain jacket and waterproof shoesfrequent rain
- Comfortable walking shoesmost places below are best reached on foot or with short walks
What to do in Old San Juan in September
Wet days call for a roof: these picks favor sit-down and indoor stops, plus a few for drier spells.
La Factoria
Unsigned cocktail bar of linked rooms on Calle San Sebastian, with salsa dancing late into the night.
Why now A sit-down stop to wait out showers in a month with 6.4 in of rain.
Castillo San Cristobal
The largest Spanish fort in the Americas, completed in 1783, guarding the land approach to the old city.
Casa Cortes ChocoBar
Cafe run by the Cortes chocolate family, serving hot chocolate with cheese, chocolate dishes and breakfast.
Why now Easy to slot in when September's rain moves in.
Plaza de Armas
Main square of the old city, in front of City Hall, with the island's Christmas tree and lit trees in December.
Why now Go early — afternoons average 86°F.
Calle de la Fortaleza
Shop-lined street ending at La Fortaleza, the governor's mansion since the 16th century, hung with wreaths at Christmas.
Why now Best first thing, before the 86°F afternoon heat.
Nearby in September
- Ponce in September~46 mi · highs 87°F, 4.3 in rain · similar daytime temperatures, drier
NASA POWER 2001–2025 monthly averages on a ~50 km grid. Comfort scores weigh temperature, rain, humidity and cloud: see how we score each month. Check a forecast before you go.
Old San Juan in September: quick answers
Is September a good time to visit Old San Juan?
It's one of the tougher months here, scoring 53/100, held back mainly by cloud cover. The best months are December – March. Expect highs of 86°F (30°C) and 6.4 in (162 mm) of rain.
How hot is Old San Juan in September?
Average highs are 86°F (30°C) and average lows 80°F (27°C), making it the 2nd-warmest month by daytime highs.
Does it rain a lot in Old San Juan in September?
Yes: about 6.4 in (162 mm) of rain falls across September on average, the wettest month of the year. The annual total is about 47.5 in (1207 mm).
What should I pack for Old San Juan in September?
Bring light, breathable clothes (highs average 86°F), sunscreen, sunglasses and a hat (strong sun this month), refillable water bottle (easy to dehydrate in the heat), quick-dry fabrics (79% average humidity) and rain jacket and waterproof shoes (frequent rain).
More on Old San Juan
Planning Old San Juan in September?
Plan it together in TripsCircle: one itinerary, one shared packing list and costs split as you go.