San Juan (Puerto Rico) weather in May

May in San Juan: sweltering, rainy, with clean air — fine if you can take 36°C afternoons.

Updated September 2026 · climate normals from ERA5 reanalysis

San Juan🇵🇷 Puerto Rico · Greater Antilles · City70
  1. 77Jan
  2. 75Feb
  3. 77Mar
  4. 72Apr
  5. 70May
  6. 70Jun
  7. 66Jul
  8. 64Aug
  9. 61Sep
  10. 63Oct
  11. 64Nov
  12. 73Dec

#6 of 12 months in San Juan · #1039 of 1413 destinations to visit in May · comfort 70/100 (tier B)

Days
31°C
Nights
24°C
Wet days
6
Sun
11.5 h
Humidity
78%
Daylight
13 h
San Juan, Puerto Rico
Photo: Diego F. Parra · Pexels

Traveller notes on San Juan in May

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.
MostRainOfAnyMonthButShowersStayBrief · May · 1 month ago · Read more on Tripadvisor ↗

Other months in San Juan

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.
TheDriestSeasonStillRains · April · 1 month ago · Read more on Tripadvisor ↗
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.
TheBaysGlowBrighterWhenItIsDry · December · 1 month ago · Read more on Tripadvisor ↗
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.
SunAQuarterMileAway · February · 1 month ago · Read more on Tripadvisor ↗
March is the month San Juan-forum regulars put at the top for beach days: one of the driest of the year, warm days, nights cool enough to notice, and sun almost throughout. Their point about rain is worth carrying - unless a storm is involved it lasts minutes, not hours, and the sun is back out straight after, which is not how visitors from the mainland expect rain to behave. The tourist strip sits on the ocean with constant trade winds, which posters credit for keeping mosquitoes down. The trade-off is company: late December to April is high season, so it is busy - though regulars are firm that this is a family destination, not a spring-break one. The record: 29.5C days feeling like 32C, 22.5C nights, 7.2 precipitation days, a 26.2C sea, AQI 32.
CondadoTradeWinds · March · 1 month ago · Read more on Tripadvisor ↗

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San Juan climate normals — May

Daytime high31°C / 89°F🔥 sweltering
Nighttime low24°C / 76°F
Feels like (high)36°C / 97°F
Sea temperature28°C / 83°F♨️ bath-warm
Rainfall83 mm / 3.3 in🌧 rainy
Rainy days6 days
Humidity78%💦 very humid
Dew point23°C / 73°F
Sunshine11.5 h/day
Daylight13 h
Wind19 km/h / 12 mph
Air quality (US AQI)30🍃 good

Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.

Crowds in San Juan in May

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 seasonan ordinary month(estimated)

JFMAMJJASOND

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.

JFMAMJJASOND

What's on in San Juan in May

Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.

  • Rule

    El Yunque timed reservation

    1 Jan – 31 DecBook earlyClosures

    The 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 early

    Laguna 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.

  • Nature

    Leatherback nesting

    1 Mar – 15 Jul · usuallyTurtle nesting

    Leatherbacks come up the north-coast beaches through spring, and volunteer groups patrol the Pinones and Dorado sand at night. Nests are staked and the lights nearest them get shaded.

  • Hazard

    Sargassum drift

    1 Apr – 31 Aug · usuallySargassum season

    The 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 ↗

What's on around the world in May →

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?

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San Juan in May — FAQ

Is May a good time to visit San Juan?
May in San Juan: sweltering, rainy, with clean air — fine if you can take 36°C afternoons. It ranks #6 of 12 months for San Juan on SeasonMap's comfort score (70/100).
What is the weather like in San Juan in May?
In May, San Juan averages a daily high of 31.4°C and a low of 24.3°C, with about 82.7 mm of rain over roughly 5.6 rainy days.
What is the air quality in San Juan in May?
San Juan has a mean US Air Quality Index of about 30 in May.

Within 300 km: Charlotte Amalie's St Thomas Carnival on 26 Apr – 2 May, and Punta Cana's Turtle nesting on the east coast around 15 Mar – 15 Nov.