San Juan weather in May

In May, San Juan sees average daytime highs of 29°C and overnight lows near 24°C, with 112 mm of rain across 16.2 wet days and about 12.9 hours of daylight. It is the 6th-warmest and 3rd-wettest month of the year here.

Day-to-day highs hold fairly steady near 29°C through the month. The sky is clear or mostly clear about 24% of the time in May, and the air most often feels oppressive.

Daylight stretches from about 12 h 42 min at the start of May to 13 hours by month's end. Set against the rest of the year, May is San Juan's 11th-clearest and 9th-windiest month. For the whole year in context, see San Juan's year-round climate.

Daytime high
29°
6th warmest
Overnight low
24°
7th coldest
Rainfall
112 mm
16.2 wet days
Daylight
12 h 54 min
5:55 AM – 6:47 PM
Cloud cover
64%
11th clearest
Wind
14 km/h
9th windiest
Solar energy
6.33 kWh/m²
Travel score
4.7
out of 10

San Juan is capital of Puerto Rico.

Density
3,479/km²
people per km²
Founded
1521

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 29°C through the month.

A typical May day in San Juan reaches about 29°C in the afternoon and slips back to 24°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 28°C and 31°C. Set against its neighbours, May runs on par with April and about 1°C cooler than June.

20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
12924
22924
32924
42924
52924
62924
72924
82924
92924
102924
112924
122924
132924
142924
152924
162924
172924
182924
192924
202924
212924
222924
232924
242925
252925
262925
272925
282925
292925
303025
313025

How May really feels in San Juan

Once humidity and wind are folded in, May averages 19 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
19
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

The story in May is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

San Juan weather by month

How May compares with the rest of the year at a glance. May is the 6th-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan27° / 23°3910.4116.8
Feb27° / 22°287.611.47.1
Mar28° / 23°398.411.96.9
Apr28° / 23°721112.45.8
May29° / 24°11216.212.94.7
Jun30° / 25°6813.913.14.5
Jul30° / 25°8016.5134.4
Aug30° / 25°9518.712.64.0
Sep30° / 25°13120.812.13.7
Oct29° / 25°12520.511.64.0
Nov28° / 24°11218.211.14.9
Dec27° / 23°4812.210.96.4

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 24% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 22% of May, with mostly cloudy or overcast conditions the remaining 54%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16337
26139
36040
45941
55743
65545
75446
85248
95149
104951
114852
124753
134555
144357
154357
164258
174159
184159
194060
203961
213961
223961
233862
243862
253862
263961
274060
284060
294159
304159
314159

Chance of precipitation in May

Any precipitation

San Juan gets around 112 mm of rain over 16.2 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 51% and peaks near 53% on the wettest days.

0%20%40%60%151015202531
Rain chance (%)
147
248
348
449
550
651
751
852
952
1053
1153
1253
1353
1453
1553
1652
1752
1852
1952
2052
2152
2252
2352
2452
2552
2652
2752
2851
2951
3050
3150

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

Most of May feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, May lands in the oppressive band about 85% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202531
Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1123751
2122761
3121771
4120781
5118792
6117802
7116812
8115822
9114823
10012853
11011863
12010864
1309874
1408884
1507885
1606895
1706886
1805896
1904897
2004897
2103898
2203898
2303889
24038710
25028810
26028711
27028612
28028513
29028513
30028414
31028414

Wind in May

Winds average 14 km/h in May.

Across May, daily wind ranges from about 14 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
114light breeze
214light breeze
314light breeze
414light breeze
514light breeze
614light breeze
714light breeze
814light breeze
914light breeze
1014light breeze
1114light breeze
1214light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1714light breeze
1814light breeze
1914light breeze
2014light breeze
2114light breeze
2214light breeze
2314light breeze
2414light breeze
2514light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze
3114light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 12 h 42 min at the start of May to 13 hours by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 18 minutes over May. Sunrise moves from 6:02 AM to 5:51 AM, and sunset from 6:41 PM to 6:52 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
112.76:026:41
212.76:016:42
312.76:016:42
412.76:006:42
512.76:006:43
612.75:596:43
712.75:596:43
812.85:586:44
912.85:586:44
1012.85:576:44
1112.85:576:45
1212.85:566:45
1312.85:566:46
1412.85:556:46
1512.95:556:46
1612.95:556:47
1712.95:546:47
1812.95:546:47
1912.95:546:48
2012.95:536:48
2112.95:536:49
2212.95:536:49
2312.95:536:49
2413.05:526:50
2513.05:526:50
2613.05:526:50
2713.05:526:51
2813.05:526:51
2913.05:516:52
3013.05:516:52
3113.05:516:52

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 6.33 kWh/m².

For context, solar energy here swings from a low near 4.34 kWh/m² to a high of 6.56 kWh/m² in June across the year — May's 6.33 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
16.5Intense
26.4Intense
36.4Intense
46.4Intense
56.4Intense
66.4Intense
76.4Intense
86.4Intense
96.4Intense
106.4Intense
116.4Intense
126.3Intense
136.3Intense
146.3Intense
156.3Intense
166.3Intense
176.3Intense
186.3Intense
196.3Intense
206.3Intense
216.3Intense
226.3Intense
236.3Intense
246.3Intense
256.3Intense
266.3Intense
276.4Intense
286.4Intense
296.4Intense
306.4Intense
316.4Intense
Planning a trip in May

Hazard calendar for San Juan

In seasonPeak

None of San Juan's seasonal hazards are active in May. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

San Juan sits in the Atlantic hurricane belt; the season peaks August–October.

San Juan sees seasonal dust haze (July), heaviest in July.

Atlantic hurricane
Dust
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is May a good time to visit San Juan?

Our two travel scores rate May for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

4.7
Sightseeing
7th-best month of the year
6.0
Beach & pool
7th-best month of the year

May is a reasonable time to visit San Juan for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for San Juan in May

From May's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In May, San Juan sees daytime highs around 29°C and nights near 24°C. Pack light clothes, rain gear and sun protection. About 16 days see rain.

light clothesrain gearsun protection

Sea temperature near San Juan in May

The nearest coast averages about 27°C in May — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 18 km away) is warmest in September at about 29°C and coldest in February near 26°C.

The water stays above 20°C all year — warm enough for a swim any month.

24°26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan27Warm
Feb26Warm
Mar26Warm
Apr27Warm
May27Warm
Jun28Warm
Jul28Tropical
Aug29Tropical
Sep29Tropical
Oct29Tropical
Nov28Tropical
Dec27Warm

UV index in San Juan in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 11 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in San Juan peaks around April 13 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 at about 7 (high).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecVery highExtremeVery highApr 13UV 13Dec 16UV 7
UV index (midday)Level
Jan8Very high
Feb10Extreme
Mar12Extreme
Apr13Extreme
May11Extreme
Jun12Extreme
Jul12Extreme
Aug12Extreme
Sep12Extreme
Oct10Very high
Nov8Very high
Dec7High

Air quality in San Juan in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.

Air quality in San Juan is worst in July — around 24 µg/m³ PM2.5 (moderate), about 4.6× the cleanest month (January, 5 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1324 µg/m³Jan 15 µg/m³
PM2.5 (µg/m³)Level
Jan5Good
Feb7Good
Mar7Good
Apr8Good
May14Moderate
Jun23Moderate
Jul24Moderate
Aug20Moderate
Sep15Moderate
Oct15Moderate
Nov8Good
Dec5Good
Location & terrain

Where is San Juan?

San Juan sits at 18.5°N, 66.1°W, 7 m above sea level, in Puerto Rico. The nearest listed city is Cataño, 3.0 km away.

Trujillo AltoCarolinaCaguas

Topography around San Juan

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of San Juan.

Within 3 km, the terrain around San Juan has only modest variations in elevation — a maximum elevation change of 42 m around an average of 2 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 289 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,308 m.

The land around San Juan is covered by water (81%) within 3 km, water (56%) and artificial surfaces (24%) within 16 km, and water (58%) and trees (32%) within 80 km.

3 km
42 m
16 km
289 m
80 km
1,308 m
treesgrasslandartificial surfacesbare terrainwaterwetlandmangroves
May weather nearby: Cataño 3.0 km · Levittown 8.0 km · Bayamón 9.0 km · Guaynabo 12 km · Candelaria 13 km · Trujillo Alto 16 km · Carolina 18 km · Caguas 27 km

Puerto Rico travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 78% of US
price level, 2025
GDP per capita
$40,620
2025
Happiness
7.0 / 10
World Happiness, 2015
Safe drinking water
99%
of population, 2024
Homicide rate
14.6
per 100k, 2023
Income group
High
World Bank
Religion
Roman Catholic 56%Protestant 33%none 7%other 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for San Juan (18.4663°, -66.1057°, elevation 7 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).