San Juan climate

Name: San Juan
Address: PR

San Juan is warmest in August, with average highs of 31 °C, and coldest in February, when nights average 21 °C. September is the wettest month (128 mm) and February the driest (31 mm). Figures are 1991–2020 climate normals.

Across a full year San Juan averages 903 mm of rain and 364 days above 25 °C.

Puerto Rico · 7 m elevation · population 418,140 · 1991–2020 normals

Temperature below 0 °C to above 30 °C Rain band height is that month’s share of the wettest month

Warmest month August 31 °C
Coldest month February 21 °C
Driest month February 31 mm
Wettest month September 128 mm
Least cloud February 36 % cloud
Hottest on record May 35 °C
Coldest on record January 17 °C
Warmest sea September 29 °C

What to expectSan Juan through the year

San Juan has a clear annual cycle: average daily highs run from 28 °C in February to 31 °C in August, a swing of 3.3 °C in mean temperature across the year.

Counted across a normal year, 364 days a year reach 25 °C, 181 of them reach 30 °C. The warmest reading in the 1991–2020 record is 35 °C, in May.

Rain is strongly seasonal. September averages 128 mm against 31 mm in February — 4.1 times as much. Planning around the dry months matters more here than planning around temperature.

The sea off San Juan is warmest in September at 29 °C and coldest in February at 26 °C. Sea temperature lags the air by a month or two, which is why late summer swims warmer than early summer at the same air temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	27.9 °C	43 mm	38 %
February	28.5 °C	31 mm	36 %
March	29.3 °C	41 mm	39 %
April	29.9 °C	73 mm	44 %
May	30.4 °C	108 mm	60 %
June	31.2 °C	62 mm	58 %
July	31.4 °C	68 mm	54 %
August	31.5 °C	82 mm	57 %
September	31.1 °C	128 mm	63 %
October	30.3 °C	113 mm	58 %
November	28.9 °C	105 mm	52 %
December	28.1 °C	49 mm	41 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C
January	27.9 °C	21.5 °C	24.1 °C	31.6 °C	17.1 °C	31	2
February	28.5 °C	21.3 °C	24.3 °C	32.8 °C	17.9 °C	28	4
March	29.3 °C	21.5 °C	24.8 °C	33.5 °C	18.4 °C	31	10
April	29.9 °C	22.3 °C	25.5 °C	34.2 °C	19.7 °C	30	14
May	30.4 °C	23.4 °C	26.3 °C	35.1 °C	20.1 °C	31	19
June	31.2 °C	24.3 °C	27.2 °C	34.5 °C	22.5 °C	30	25
July	31.4 °C	24.5 °C	27.4 °C	34.7 °C	22.9 °C	31	27
August	31.5 °C	24.7 °C	27.5 °C	34.8 °C	22.9 °C	31	28
September	31.1 °C	24.5 °C	27.2 °C	34.4 °C	22.5 °C	30	25
October	30.3 °C	24.0 °C	26.5 °C	35.0 °C	22.0 °C	31	20
November	28.9 °C	23.1 °C	25.4 °C	32.4 °C	20.1 °C	30	5
December	28.1 °C	22.1 °C	24.6 °C	31.8 °C	17.7 °C	31	2

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind	Sea temp
January	43 mm	10	11 h/day	38 %	80 %	20 km/h	26.5 °C
February	31 mm	8	12 h/day	36 %	77 %	21 km/h	26.1 °C
March	41 mm	9	12 h/day	39 %	74 %	20 km/h	26.1 °C
April	73 mm	12	13 h/day	44 %	76 %	19 km/h	26.6 °C
May	108 mm	16	13 h/day	60 %	79 %	19 km/h	27.2 °C
June	62 mm	14	13 h/day	58 %	78 %	21 km/h	27.9 °C
July	68 mm	16	13 h/day	54 %	78 %	22 km/h	28.2 °C
August	82 mm	18	13 h/day	57 %	80 %	21 km/h	28.6 °C
September	128 mm	20	12 h/day	63 %	82 %	18 km/h	28.9 °C
October	113 mm	20	12 h/day	58 %	84 %	16 km/h	28.9 °C
November	105 mm	18	11 h/day	52 %	84 %	17 km/h	28.3 °C
December	49 mm	13	11 h/day	41 %	82 %	20 km/h	27.3 °C

How San Juan compares

The same four figures for nearby destinations, so the numbers above have something to be read against. Summer high is the warmest month's average high; winter low is the coldest month's average low.

Destination	Summer high	Winter low	Rain per year	Days above 25 °C
San Juan	31 °C	21 °C	903 mm	364
Carolina · Puerto Rico	31 °C	21 °C	1,200 mm	364
Charlotte Amalie · U.S. Virgin Islands	28 °C	24 °C	858 mm	338
Road Town · British Virgin Islands	28 °C	24 °C	825 mm	336
La Romana · Dominican Republic	32 °C	22 °C	673 mm	365
San Pedro de Macorís · Dominican Republic	31 °C	22 °C	737 mm	364
Gustavia · Saint Barthelemy	28 °C	24 °C	757 mm	342

Where San Juan ranks

Ranking	Position	Value
The warmest places in North America in November	21st of 50	29 °C
The warmest places in North America in October	24th of 50	30 °C
The warmest places in North America in December	27th of 50	28 °C
The warmest places in North America in January	30th of 50	28 °C
The warmest places in North America in February	31st of 50	28 °C
The warmest places in North America year-round	36th of 50	30 °C

Planning a trip? See the best time to visit San Juan.

QuestionsCommon questions about San Juan’s climate

When is the best time to visit San Juan?

That depends on what you want, so the honest answer is a comparison rather than a single month. January, February, December sit closest to 20 °C on average, August is the warmest month and February the driest. The month-by-month table above has the full picture.

How hot does San Juan get?

In August, the warmest month, daily highs average 31 °C. About 181 days a year pass 30 °C. The highest value in the 1991–2020 record is 35 °C.

How cold does it get in winter?

Nights average 21 °C in February, the coldest month. Freezing nights are not part of a normal year here.

Which month is wettest in San Juan?

September, averaging 128 mm over 20 days with rain. The driest month is February with 31 mm. The year as a whole averages 903 mm.

Are these figures a forecast?

No. They are 1991–2020 climate normals: the average of thirty years, which describes what a month is usually like in San Juan rather than what any particular week will bring. Individual years can differ substantially from the normal.

Data sources and method

ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
Open-Meteo — Open-Meteo.com. CC BY 4.0
NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
GeoNames — GeoNames.org. CC BY 4.0

Normal period: 1991–2020
Data point: 18.466°, -66.106° , 7 m above sea level (the coordinates the reanalysis values are taken for)
Dataset version: era5-1991-2020-scores1.1
Last processed: 1 August 2026

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: monthly rankings, daylight hours, beach and comfort scores. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.