Cotonou weather in September

In September, Cotonou sees average daytime highs of 26°C and overnight lows near 25°C, with 105 mm of rain across 18 wet days and about 12 hours of daylight. It is the 10th-warmest and 5th-wettest month of the year here.

Day-to-day highs hold fairly steady near 26°C through the month. The sky is clear or mostly clear about 11% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 06 min at the start of September to 12 hours by month's end. Set against the rest of the year, September is Cotonou's 8th-clearest and 4th-windiest month. For the whole year in context, see Cotonou's year-round climate.

Daytime high
26°
10th warmest
Overnight low
25°
3rd coldest
Rainfall
105 mm
18 wet days
Daylight
12 hours
6:44 AM – 6:46 PM
Cloud cover
73%
8th clearest
Wind
19 km/h
4th windiest
Solar energy
4.7 kWh/m²
Travel score
5.2
out of 10

Cotonou is city in Benin, seat of the government.

Density
8,595/km²
people per km²

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 26°C through the month.

A typical September day in Cotonou reaches about 26°C in the afternoon and slips back to 25°C overnight — a 1°C spread between the day's warmth and the night's chill. On most days the high lands between 25°C and 26°C. Set against its neighbours, September runs about 1°C warmer than August and about 1°C cooler than October.

20°23°25°28°30°151015202530
Avg high (°C)Avg low (°C)
12524
22524
32524
42525
52525
62525
72525
82525
92525
102625
112625
122625
132625
142625
152625
162625
172625
182625
192625
202625
212625
222625
232625
242625
252625
262625
272625
282625
292625
302625

How September really feels in Cotonou

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.

Cotonou weather by month

How September compares with the rest of the year at a glance. September is the 10th-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan28° / 26°216.611.77.1
Feb28° / 27°277.811.86.4
Mar29° / 27°4812.5125.3
Apr29° / 27°7315.712.14.8
May28° / 27°16423.412.34.0
Jun27° / 26°25926.112.43.9
Jul26° / 25°13218.912.35.2
Aug25° / 24°7313.312.26.1
Sep26° / 25°10518125.2
Oct27° / 26°11020.211.95.0
Nov28° / 27°4913.811.75.7
Dec28° / 27°277.611.66.9

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 11% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 71%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
12674
22674
32773
42773
52773
62773
72872
82872
92872
102872
112872
122872
132971
142971
152971
162971
173070
182971
193070
203070
213070
223169
233169
243169
253268
263268
273367
283367
293367
303466

Chance of precipitation in September

Any precipitation

Cotonou gets around 105 mm of rain over 18 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 60% and peaks near 66% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
153
254
354
455
555
656
756
856
957
1057
1158
1259
1360
1460
1561
1661
1762
1862
1962
2063
2163
2264
2364
2464
2564
2665
2765
2865
2965
3066

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 99% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
11000
21000
31000
41000
51000
61000
71000
81000
91000
101000
111000
121000
131000
141000
151000
161000
171000
181000
19991
20991
21991
22991
23991
24982
25982
26982
27982
28982
29973
30973

Wind in September

Winds average 19 km/h in September.

Across September, daily wind ranges from about 18 km/h on the calmest days to 21 km/h at its breeziest. It stays fairly steady from day to day.

0510152025151015202530
Wind speed (km/h)Feels
121breezy
221breezy
321breezy
421breezy
521breezy
621breezy
720breezy
820breezy
920breezy
1020breezy
1120breezy
1220light breeze
1320light breeze
1420light breeze
1519light breeze
1619light breeze
1719light breeze
1819light breeze
1919light breeze
2019light breeze
2119light breeze
2218light breeze
2318light breeze
2418light breeze
2518light breeze
2618light breeze
2718light breeze
2818light breeze
2918light breeze
3018light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 06 min at the start of September to 12 hours by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 6 minutes over September. Sunrise moves from 6:46 AM to 6:41 AM, and sunset from 6:54 PM to 6:38 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.16:466:54
212.16:466:53
312.16:466:53
412.16:466:52
512.16:466:52
612.16:466:51
712.16:456:51
812.16:456:50
912.16:456:50
1012.16:456:49
1112.16:456:48
1212.16:446:48
1312.16:446:47
1412.06:446:47
1512.06:446:46
1612.06:446:46
1712.06:436:45
1812.06:436:45
1912.06:436:44
2012.06:436:43
2112.06:436:43
2212.06:426:42
2312.06:426:42
2412.06:426:41
2512.06:426:41
2612.06:426:40
2712.06:426:40
2812.06:416:39
2912.06:416:39
3012.06:416:38

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.7 kWh/m².

For context, solar energy here swings from a low near 4.22 kWh/m² to a high of 5.6 kWh/m² in March across the year — September's 4.7 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.6Bright
24.6Bright
34.6Bright
44.6Bright
54.6Bright
64.6Bright
74.6Bright
84.7Bright
94.7Bright
104.7Bright
114.7Bright
124.7Bright
134.7Bright
144.7Bright
154.7Bright
164.7Bright
174.7Bright
184.7Bright
194.7Bright
204.7Bright
214.7Bright
224.8Bright
234.8Bright
244.8Bright
254.8Bright
264.8Bright
274.8Bright
284.8Bright
294.8Bright
304.8Bright
Planning a trip in September

Hazard calendar for Cotonou

In seasonPeak

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

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

Cotonou sees seasonal dust haze (January–April), heaviest in February.

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

Is September a good time to visit Cotonou?

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

5.2
Sightseeing
7th-best month of the year
5.0
Beach & pool
9th-best month of the year

September is a reasonable time to visit Cotonou for sightseeing.

What to pack for Cotonou in September

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

In September, Cotonou sees daytime highs around 26°C and nights near 25°C. Pack rain gear. Worth having: light clothes and sun protection. About 18 days see rain.

rain gearlight clothessun protection

Sea temperature near Cotonou in September

The nearest coast averages about 26°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in May at about 29°C and coldest in August near 25°C.

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

24°26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan28Warm
Feb28Tropical
Mar29Tropical
Apr29Tropical
May29Tropical
Jun28Warm
Jul26Warm
Aug25Warm
Sep26Warm
Oct27Warm
Nov29Tropical
Dec28Tropical

UV index in Cotonou 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 Cotonou peaks around April 10 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 17 at about 8 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecVery highExtremeExtremeVery highApr 10UV 13Dec 17UV 8
UV index (midday)Level
Jan9Very high
Feb10Very high
Mar13Extreme
Apr13Extreme
May11Extreme
Jun11Extreme
Jul10Extreme
Aug10Very high
Sep12Extreme
Oct12Extreme
Nov9Very high
Dec8Very high

Air quality in Cotonou 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 Cotonou is worst in January — around 78 µg/m³ PM2.5 (unhealthy), about 7.7× the cleanest month (September, 10 µg/m³).

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

020406080JanFebMarAprMayJunJulAugSepOctNovDecUnhealthyModerateGoodModerateJan 1676 µg/m³Sep 1810 µg/m³
PM2.5 (µg/m³)Level
Jan78Unhealthy
Feb61Unhealthy
Mar28Moderate
Apr24Moderate
May15Moderate
Jun15Moderate
Jul16Moderate
Aug13Moderate
Sep10Good
Oct12Good
Nov19Moderate
Dec61Unhealthy
Location & terrain

Where is Cotonou?

Cotonou sits at 6.4°N, 2.4°E, 7 m above sea level, in Benin. The nearest listed city is Godomè, 8.0 km away.

Topography around Cotonou

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

Within 3 km, the terrain around Cotonou has only modest variations in elevation — a maximum elevation change of 13 m around an average of 5 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 33 m; within 80 km, only modest variations in elevation — a maximum elevation change of 171 m.

The land around Cotonou is covered by artificial surfaces (76%) within 3 km, water (66%) and artificial surfaces (20%) within 16 km, and trees (37%) and water (36%) within 80 km.

3 km
13 m
16 km
33 m
80 km
171 m
treesshrubsgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Godomè 8.0 km · Ganvié 11 km · Abomey-Calavi 12 km · Ekpé 13 km · Semi 22 km · Porto-Novo 25 km · Missérété 29 km · Zinvié 29 km

Benin travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / E
220 V · 50 Hz
Prices
≈ 34% of US
price level, 2025
GDP per capita
$1,658
2025
Happiness
4.4 / 10
World Happiness, 2025
Safe drinking water
18%
of population, 2024
Homicide rate
1.1
per 100k, 2017
Road deaths
26.8
per 100k/yr, 2019
Income group
Lower middle
World Bank
English
Very low
EF EPI 406
Religion
Muslim 28%Roman Catholic 26%Protestant 14%Vodoun 12%

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 Cotonou (6.3654°, 2.4183°, 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. 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).