Cayey weather in September

In September, Cayey sees average daytime highs of 28°C and overnight lows near 24°C, with 143 mm of rain across 21.6 wet days and about 12.1 hours of daylight. It is the 3rd-warmest and 1st-wettest month of the year here.

Day-to-day highs hold fairly steady near 28°C through the month. The sky is clear or mostly clear about 23% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 24 min at the start of September to 11 h 54 min by month's end. Set against the rest of the year, September is Cayey's 12th-clearest and 11th-windiest month. For the whole year in context, see Cayey's year-round climate.

Daytime high
28°
3rd warmest
Overnight low
24°
11th coldest
Rainfall
143 mm
21.6 wet days
Daylight
12 h 06 min
6:16 AM – 6:22 PM
Cloud cover
66%
12th clearest
Wind
13 km/h
11th windiest
Solar energy
5.82 kWh/m²
Travel score
4.2
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 28°C through the month.

A typical September day in Cayey reaches about 28°C in the afternoon and slips back to 24°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 29°C. Set against its neighbours, September runs on par with August and on par with October.

20°23°25°28°30°151015202530
Avg high (°C)Avg low (°C)
12924
22924
32824
42824
52824
62824
72824
82824
92824
102824
112824
122824
132824
142824
152824
162824
172824
182824
192824
202824
212824
222824
232824
242824
252824
262824
272824
282824
292824
302824

How September really feels in Cayey

Once humidity and wind are folded in, September averages 0 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
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Cayey weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan26° / 22°3210.8116.9
Feb26° / 21°279.411.47.0
Mar26° / 22°4010.811.96.8
Apr27° / 22°5913.712.46.1
May27° / 23°9818.212.85.3
Jun28° / 24°6415.913.15.2
Jul28° / 24°7515.5135.1
Aug29° / 24°9618.812.64.6
Sep28° / 24°14321.612.14.2
Oct28° / 24°12221.411.64.7
Nov27° / 23°911711.15.5
Dec26° / 22°3911.610.96.7

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 23% of the time in September, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 21% of September, with mostly cloudy or overcast conditions the remaining 56%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14753
24753
34753
44753
54852
64852
74852
84852
94852
104852
114852
124852
134654
144654
154555
164456
174456
184357
194159
204060
214159
224060
234060
243961
253961
264060
274060
284159
294159
304159

Chance of precipitation in September

Any precipitation

Cayey gets around 143 mm of rain over 21.6 wet days in September, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 71% and peaks near 75% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
166
266
366
466
566
667
767
868
968
1069
1170
1271
1371
1472
1572
1673
1773
1874
1974
2074
2175
2275
2375
2475
2575
2675
2774
2874
2974
3074

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the oppressive band about 95% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Muggy (%)Oppressive (%)Miserable (%)
10955
20955
30955
40955
50955
60955
70955
80955
90946
100946
110946
120946
130946
140946
150946
160946
170946
180946
190946
200946
210946
220955
230955
240955
250955
261954
271954
281954
291954
301954

Wind in September

Winds average 13 km/h in September.

Across September, daily wind ranges from about 13 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
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
1313light breeze
1413light breeze
1513light breeze
1613light breeze
1713light breeze
1813light breeze
1913light breeze
2013light breeze
2113light breeze
2213light breeze
2313light breeze
2413light breeze
2513light breeze
2613light breeze
2713light breeze
2813light breeze
2913light breeze
3013light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 24 min at the start of September to 11 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 30 minutes over September. Sunrise moves from 6:14 AM to 6:18 AM, and sunset from 6:35 PM to 6:10 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.46:146:35
212.36:146:34
312.36:146:33
412.36:146:33
512.36:146:32
612.36:146:31
712.36:156:30
812.26:156:29
912.26:156:28
1012.26:156:27
1112.26:156:26
1212.26:156:26
1312.26:156:25
1412.16:166:24
1512.16:166:23
1612.16:166:22
1712.16:166:21
1812.16:166:20
1912.06:166:19
2012.06:176:18
2112.06:176:18
2212.06:176:17
2312.06:176:16
2412.06:176:15
2511.96:176:14
2611.96:186:13
2711.96:186:12
2811.96:186:11
2911.96:186:10
3011.96:186:10

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.82 kWh/m².

For context, solar energy here swings from a low near 4.46 kWh/m² to a high of 6.55 kWh/m² in April across the year — September's 5.82 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.1Intense
26.1Intense
36.1Intense
46.1Intense
56.1Intense
66.0Intense
76.0Intense
86.0Intense
96.0Bright
106.0Bright
115.9Bright
125.9Bright
135.9Bright
145.9Bright
155.8Bright
165.8Bright
175.8Bright
185.8Bright
195.7Bright
205.7Bright
215.7Bright
225.7Bright
235.6Bright
245.6Bright
255.6Bright
265.6Bright
275.5Bright
285.5Bright
295.5Bright
305.5Bright
Planning a trip in September

Hazard calendar for Cayey

In seasonPeak

In September, Cayey sits inside its atlantic hurricane and rainy season season. The full year is below, with each hazard's peak months called out.

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

Cayey's rainy season runs July–November, when most of the year's rain falls.

Cayey sees seasonal dust haze (July), heaviest in July.

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

Is September a good time to visit Cayey?

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

4.2
Sightseeing
12th-best month of the year
5.0
Beach & pool
12th-best month of the year

September is a reasonable time to visit Cayey for sightseeing.

What to pack for Cayey in September

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

In September, Cayey sees daytime highs around 28°C and nights near 24°C. Pack light clothes and rain gear. Worth having: sun protection. About 22 days see rain.

light clothesrain gearsun protection

Sea temperature near Cayey in September

The nearest coast averages about 29°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 27 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
May28Warm
Jun28Tropical
Jul28Tropical
Aug29Tropical
Sep29Tropical
Oct29Tropical
Nov28Tropical
Dec28Warm

UV index in Cayey in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 12 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Cayey peaks around April 12 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 at about 7 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecVery highExtremeVery highApr 12UV 13Dec 16UV 7
UV index (midday)Level
Jan8Very high
Feb10Extreme
Mar13Extreme
Apr13Extreme
May12Extreme
Jun12Extreme
Jul12Extreme
Aug12Extreme
Sep12Extreme
Oct10Very high
Nov8Very high
Dec7High

Air quality in Cayey in September

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Cayey is worst in July — around 25 µg/m³ PM2.5 (moderate), about 4.7× the cleanest month (January, 5 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1125 µg/m³Jan 15 µg/m³
PM2.5 (µg/m³)Level
Jan5Good
Feb7Good
Mar7Good
Apr9Good
May14Moderate
Jun24Moderate
Jul25Moderate
Aug20Moderate
Sep15Moderate
Oct15Moderate
Nov8Good
Dec5Good
Location & terrain

Where is Cayey?

Cayey sits at 18.1°N, 66.2°W, 397 m above sea level, in Puerto Rico. The nearest listed city is Guayama, 15 km away.

CaguasGuaynaboTrujillo AltoBayamónCandelariaHumacaoCataño

Topography around Cayey

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

Within 3 km, the terrain around Cayey has significant variations in elevation — a maximum elevation change of 462 m around an average of 482 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 892 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,308 m.

The land around Cayey is covered by trees (68%) within 3 km, trees (81%) within 16 km, and water (60%) and trees (32%) within 80 km.

3 km
462 m
16 km
892 m
80 km
1,308 m
treesshrubsgrasslandartificial surfaceswater
September weather nearby: Guayama 15 km · Caguas 18 km · Guaynabo 28 km · Trujillo Alto 32 km · Bayamón 32 km · Candelaria 33 km · Humacao 36 km · Cataño 37 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 Cayey (18.1119°, -66.166°, elevation 397 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).