Arecibo weather in September

In September, Arecibo sees average daytime highs of 30°C and overnight lows near 25°C, with 154 mm of rain across 22.3 wet days and about 12.1 hours of daylight. It is the 3rd-warmest and 2nd-wettest month of the year here.

Day-to-day highs hold fairly steady near 30°C through the month. The sky is clear or mostly clear about 19% 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 Arecibo's 12th-clearest and 11th-windiest month. For the whole year in context, see Arecibo's year-round climate.

Daytime high
30°
3rd warmest
Overnight low
25°
11th coldest
Rainfall
154 mm
22.3 wet days
Daylight
12 h 06 min
6:18 AM – 6:24 PM
Cloud cover
66%
12th clearest
Wind
12 km/h
11th windiest
Solar energy
5.8 kWh/m²
Travel score
3.6
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 30°C through the month.

A typical September day in Arecibo reaches about 30°C in the afternoon and slips back to 25°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 29°C and 31°C. Set against its neighbours, September runs on par with August and on par with October.

20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
13025
23025
33025
43025
53025
63025
73025
83025
93025
103025
113025
123025
133025
143025
153025
163025
173025
183025
193025
203025
213025
223025
233025
243025
253025
263025
273025
283025
293025
303025

How September really feels in Arecibo

Once humidity and wind are folded in, September averages 30 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
30
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

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

Arecibo weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan27° / 22°419.5117.0
Feb27° / 22°368.111.47.0
Mar27° / 22°591011.96.7
Apr28° / 22°10713.712.45.8
May29° / 24°16518.312.94.5
Jun30° / 24°9213.813.14.6
Jul30° / 25°7914.9134.5
Aug30° / 25°10119.612.63.9
Sep30° / 25°15422.312.13.6
Oct29° / 24°13821.411.64.0
Nov28° / 23°11317.511.15.2
Dec27° / 23°4811.410.96.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 19% of the time in September, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 23% of September, with mostly cloudy or overcast conditions the remaining 58%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14357
24456
34456
44456
54555
64456
74555
84555
94456
104456
114555
124456
134456
144357
154357
164357
174159
184159
194060
203961
214060
223961
234060
243961
254060
264060
274159
284159
294258
304258

Chance of precipitation in September

Any precipitation

Arecibo gets around 154 mm of rain over 22.3 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 74% and peaks near 76% on the wettest days.

0%20%40%60%80%151015202530
Rain chance (%)
172
271
371
471
571
671
772
872
972
1073
1173
1274
1374
1475
1575
1675
1776
1876
1976
2076
2176
2276
2376
2476
2575
2675
2774
2874
2973
3073

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 66% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
16238
26337
36337
46436
56436
66535
76535
86535
96634
106634
116733
126733
136733
146832
156832
166832
176832
186733
196733
206733
216733
226733
236733
246733
256733
266733
276832
286832
296832
306931

Wind in September

Winds average 12 km/h in September.

Across September, daily wind ranges from about 11 km/h on the calmest days to 13 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
412light breeze
512light breeze
612light breeze
712light breeze
812light breeze
912light breeze
1012light breeze
1112light breeze
1212calm
1312calm
1412calm
1512calm
1612calm
1712calm
1812calm
1911calm
2011calm
2111calm
2211calm
2311calm
2411calm
2511calm
2611calm
2711calm
2811calm
2911calm
3011calm

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 6:16 AM to 6:21 AM, and sunset from 6:38 PM to 6:12 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.46:166:38
212.46:166:37
312.36:166:36
412.36:166:35
512.36:166:34
612.36:166:33
712.36:176:32
812.26:176:32
912.26:176:31
1012.26:176:30
1112.26:176:29
1212.26:176:28
1312.26:186:27
1412.16:186:26
1512.16:186:25
1612.16:186:24
1712.16:186:23
1812.16:186:22
1912.06:196:22
2012.06:196:21
2112.06:196:20
2212.06:196:19
2312.06:196:18
2412.06:196:17
2511.96:206:16
2611.96:206:15
2711.96:206:14
2811.96:206:13
2911.96:206:13
3011.96:216:12

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.8 kWh/m².

For context, solar energy here swings from a low near 4.4 kWh/m² to a high of 6.53 kWh/m² in June across the year — September's 5.8 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.0Intense
26.0Intense
36.0Intense
46.0Intense
56.0Intense
66.0Bright
76.0Bright
86.0Bright
95.9Bright
105.9Bright
115.9Bright
125.9Bright
135.8Bright
145.8Bright
155.8Bright
165.8Bright
175.8Bright
185.7Bright
195.7Bright
205.7Bright
215.7Bright
225.7Bright
235.6Bright
245.6Bright
255.6Bright
265.6Bright
275.6Bright
285.5Bright
295.5Bright
305.5Bright
Planning a trip in September

Hazard calendar for Arecibo

In seasonPeak

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

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

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

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

Is September a good time to visit Arecibo?

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

3.6
Sightseeing
12th-best month of the year
4.9
Beach & pool
12th-best month of the year

September is a weaker month for outdoor sightseeing in Arecibo.

What to pack for Arecibo in September

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

In September, Arecibo sees daytime highs around 30°C and nights near 25°C. Pack light clothes and rain gear. Worth having: sun protection. About 22 days see rain.

light clothesrain gearsun protection

Sea temperature near Arecibo 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 19 km away) is warmest in September at about 29°C and coldest in March 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
Jun28Tropical
Jul28Tropical
Aug29Tropical
Sep29Tropical
Oct29Tropical
Nov28Tropical
Dec27Warm

UV index in Arecibo 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 Arecibo peaks around April 12 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 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 15UV 7
UV index (midday)Level
Jan8Very high
Feb10Extreme
Mar12Extreme
Apr13Extreme
May11Extreme
Jun12Extreme
Jul12Extreme
Aug12Extreme
Sep12Extreme
Oct10Very high
Nov8Very high
Dec7High

Air quality in Arecibo 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 Arecibo is worst in July — around 24 µg/m³ PM2.5 (moderate), about 4.8× the cleanest month (January, 5 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1324 µg/m³Jan 105 µg/m³
PM2.5 (µg/m³)Level
Jan5Good
Feb7Good
Mar7Good
Apr8Good
May14Moderate
Jun23Moderate
Jul24Moderate
Aug20Moderate
Sep15Moderate
Oct15Moderate
Nov7Good
Dec5Good
Location & terrain

Where is Arecibo?

Arecibo sits at 18.5°N, 66.7°W, 7 m above sea level, in Puerto Rico. The nearest listed city is Barceloneta, 19 km away.

BarcelonetaManatíVega BajaAguadillaYaucoPonceMayagüezCandelaria

Topography around Arecibo

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

Within 3 km, the terrain around Arecibo has only modest variations in elevation — a maximum elevation change of 80 m around an average of 7 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 408 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,307 m.

The land around Arecibo is covered by water (44%) and trees (20%) within 3 km, water (45%) and trees (35%) within 16 km, and water (55%) and trees (35%) within 80 km.

3 km
80 m
16 km
408 m
80 km
1,307 m
treesgrasslandartificial surfacesbare terrainwaterwetlandmangroves
September weather nearby: Barceloneta 19 km · Manatí 24 km · Vega Baja 35 km · Aguadilla 47 km · Yauco 51 km · Ponce 52 km · Mayagüez 54 km · Candelaria 54 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 Arecibo (18.4724°, -66.7157°, 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).