San Juan (Puerto Rico) weather in August
August in San Juan: sweltering, rainy, with clean air — a gamble, with 36°C afternoons.
Updated September 2026 · climate normals from ERA5 reanalysis
#9 of 12 months in San Juan · #1031 of 1413 destinations to visit in August · comfort 64/100 (tier C)
- Days
- 32°C
- Nights
- 26°C
- Wet days
- 9
- Sun
- 11.1 h
- Humidity
- 80%
- Daylight
- 13 h

Traveller notes on San Juan in August
Other months in San Juan
Regulars are specific this technically counts as the wettest month of the year here, edging out August, though outside of hurricane season a shower typically clears within minutes rather than settling in for the day. Our row backs that hot, genuinely showery read, 31.4C reading as a hot 36C, over 24.3C nights, with 82.7mm of rain across 5.6 days and humidity at 78 percent. Regulars are consistent the dying trade-wind breezes this time of year can make the heat feel a touch more intense than earlier spring months despite similar temperatures. This remains a genuinely good month overall, brief widely scattered showers rather than an all-day soak the standard experience. The sea sits at a warm, swimmable 28.3C. The record: 11.5 hours of sun, an 18.9 kph wind and one of the cleanest air readings in this project, AQI 30.
April is the drier end of the year here and the board frames it as the good window - out of the rainy season, humidity down, temperatures from the low seventies to the mid eighties, which is our 30.1C over 23.3C. They put the sea around 79F and our column says 26.7C, near enough the same water. The qualification our row adds is the standard one for a Caribbean dry season: 98.5mm still falls, across 6.7 days, so the showers are quick and real rather than absent. Nor is it off season - a hard winter in the States fills the island in April. The wind runs 19.1 kph off the Atlantic. The record: humidity 77 percent, 11.3 hours of sun and AQI 33.
December opens the dry season without being dry: regulars put it at about four and a half inches and warn that the month can still be wet, adding that a wet day here is not a wet day at home. Our row says 79.8mm across 11.9 days, seven millimetres apiece, under 29.6C over 23.3C. The payoff they name is specific - less rain means less runoff, so the bioluminescent bays are clearer and the glow stronger. The cost is the calendar: the festive season from about mid-December to early January is the island's high season, and air fares, hotels and car hire all climb with it. The record: humidity 82 percent, 10.1 hours of sun, a 18.8 kph wind and a 27.7C sea.
February in San Juan is mid-80s Fahrenheit, a touch cooler than the rest of the year, and the whole forum conversation is about how to read the rain figure. Our row counts 9.5 precipitation days carrying 76.3mm, and regulars explain what that looks like on the ground: fast-moving, widely scattered showers that last minutes rather than hours, often falling in one spot while the sun is out a quarter of a mile away. Their standing complaint is that the forecast sites predict rain every day of the year here, so you would never book if you believed them - one visitor got two or three hours of rain across a whole February week. The record: 29.3C days that feel like 31C, 22.3C nights, 10.7 hours of sun and a 26.1C sea.
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San Juan climate normals — August
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in San Juan in August
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Shoulder seasonschool holidays in 3 of the markets that fill it, an ordinary month(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for San Juan's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherSan Juan's weather doesn't swing hard through the year — comfort stays fairly steady in every month.
What's on in San Juan in August
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Rule
El Yunque timed reservation
1 Jan – 31 DecBook earlyClosuresThe main road into the rainforest, the one with the waterfalls and the tower, needs a timed entry reservation booked ahead. Cars without one are turned round at the gate on busy mornings. Source ↗
- Nature
Bioluminescent bay nights
1 Jan – 31 DecBioluminescenceBook earlyLaguna Grande at Fajardo glows all year, but only on the dark nights: operators sell by moon phase, and a full moon washes it out entirely. Rain in the week before also thins it.
- Hazard
Sargassum drift
1 Apr – 31 Aug · usuallySargassum seasonThe city beaches at Condado and Isla Verde usually get off lightly; the east coast towards Fajardo and the offshore cays take far more. CariCOOS runs a Puerto Rico forecast that is worth ten minutes before booking. Source ↗
- Hazard
Hurricane season
1 Jun – 30 NovMaria came ashore in September 2017 and the island still plans around that month. The statistical peak is the first fortnight of September; June and November rarely deliver anything, and rates in those weeks show it. Source ↗
Nearby, and something's on
Within 300 km of San Juan — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is San Juan?
San Juan in August — FAQ
- Is August a good time to visit San Juan?
- August in San Juan: sweltering, rainy, with clean air — a gamble, with 36°C afternoons. It ranks #9 of 12 months for San Juan on SeasonMap's comfort score (64/100).
- What is the weather like in San Juan in August?
- In August, San Juan averages a daily high of 32.2°C and a low of 25.9°C, with about 104.1 mm of rain over roughly 9.3 rainy days.
- What is the air quality in San Juan in August?
- San Juan has a mean US Air Quality Index of about 34 in August.
Within 300 km: Punta Cana's Turtle nesting on the east coast around 15 Mar – 15 Nov.