Cayenne weather in September

In September, Cayenne sees average daytime highs of 30°C and overnight lows near 25°C, with 23 mm of rain across 7.2 wet days and about 12 hours of daylight. It is the 1st-warmest and 12th-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 65% 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 Cayenne's 1st-clearest and 9th-windiest month. For the whole year in context, see Cayenne's year-round climate.

Daytime high
30°
1st warmest
Overnight low
25°
12th coldest
Rainfall
23 mm
7.2 wet days
Daylight
12 hours
6:23 AM – 6:24 PM
Cloud cover
35%
1st clearest
Wind
15 km/h
9th windiest
Solar energy
6.26 kWh/m²
Travel score
5.5
out of 10

Cayenne is commune and capital city of French Guiana.

Density
2,608/km²
people per km²
Founded
1664

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 30°C through the month.

A typical September day in Cayenne 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 Cayenne

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.

Cayenne weather by month

How September compares with the rest of the year at a glance. September is the 1st-warmest and 12th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan27° / 25°24426.611.74.0
Feb27° / 25°20522.311.84.2
Mar28° / 25°17323.9124.3
Apr28° / 25°2582512.14.0
May28° / 25°41129.112.23.5
Jun28° / 25°34428.512.33.5
Jul29° / 25°18624.812.34.0
Aug30° / 25°6713.912.25.0
Sep30° / 25°237.2125.5
Oct30° / 25°4010.111.95.1
Nov29° / 25°12219.611.84.2
Dec28° / 25°25326.511.73.8

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 65% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 18%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
18416
28416
38416
48416
58416
68317
78317
88218
98119
108119
118020
128119
138119
148119
158119
168119
178218
188218
198218
208218
218218
228317
238317
248317
258317
268317
278317
288317
298218
308119

Chance of precipitation in September

Any precipitation

Cayenne gets around 23 mm of rain over 7.2 wet days in September, the driest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 25% and peaks near 26% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
126
226
326
425
525
625
725
826
926
1026
1126
1226
1326
1425
1525
1625
1724
1824
1924
2024
2124
2224
2324
2424
2524
2624
2724
2825
2925
3026

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 96% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
1973
2973
3973
4973
5973
6973
7973
8973
9973
10973
11964
12964
13964
14964
15964
16964
17964
18964
19964
20964
21964
22973
23973
24973
25973
26973
27973
28973
29964
30964

Wind in September

Winds average 15 km/h in September.

Across September, daily wind ranges from about 14 km/h on the calmest days to 15 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
515light breeze
615light breeze
715light breeze
815light breeze
915light breeze
1015light breeze
1115light breeze
1215light breeze
1315light breeze
1415light breeze
1515light breeze
1615light breeze
1715light breeze
1815light breeze
1915light breeze
2015light breeze
2115light breeze
2215light breeze
2315light breeze
2415light breeze
2515light breeze
2615light breeze
2715light breeze
2815light breeze
2915light breeze
3015light 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 6:26 AM to 6:20 AM, and sunset from 6:32 PM to 6:18 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.16:266:32
212.16:266:31
312.16:266:31
412.16:266:30
512.16:256:30
612.16:256:30
712.16:256:29
812.16:256:29
912.16:246:28
1012.16:246:28
1112.06:246:27
1212.06:246:27
1312.06:246:26
1412.06:236:25
1512.06:236:25
1612.06:236:24
1712.06:236:24
1812.06:226:23
1912.06:226:23
2012.06:226:22
2112.06:226:22
2212.06:216:21
2312.06:216:21
2412.06:216:20
2512.06:216:20
2612.06:216:19
2712.06:206:19
2812.06:206:18
2912.06:206:18
3012.06:206:18

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.26 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 4.48 kWh/m² to a high of 6.26 kWh/m² in September across the year — September's 6.26 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
16.2Intense
26.2Intense
36.2Intense
46.2Intense
56.2Intense
66.2Intense
76.2Intense
86.2Intense
96.2Intense
106.2Intense
116.2Intense
126.2Intense
136.2Intense
146.2Intense
156.2Intense
166.2Intense
176.3Intense
186.3Intense
196.3Intense
206.3Intense
216.3Intense
226.3Intense
236.3Intense
246.3Intense
256.3Intense
266.3Intense
276.3Intense
286.3Intense
296.3Intense
306.3Intense
Planning a trip in September

Hazard calendar for Cayenne

In seasonPeak

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

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

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

Is September a good time to visit Cayenne?

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

5.5
Sightseeing
1st-best month of the year
7.6
Beach & pool
1st-best month of the year

September is a reasonable time to visit Cayenne for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Cayenne in September

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

In September, Cayenne sees daytime highs around 30°C and nights near 25°C. Pack light clothes and sun protection. About 7 days see rain.

light clothessun protection

Sea temperature near Cayenne in September

The nearest coast averages about 28°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 21 km away) is warmest in July at about 28°C and coldest in January near 27°C.

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

26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan27Warm
Feb27Warm
Mar27Warm
Apr27Warm
May28Warm
Jun28Warm
Jul28Tropical
Aug28Tropical
Sep28Warm
Oct28Tropical
Nov28Warm
Dec27Warm

UV index in Cayenne 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 Cayenne peaks around April 12 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 11 at about 10 (extreme).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeApr 12UV 14Dec 11UV 10
UV index (midday)Level
Jan13Extreme
Feb13Extreme
Mar14Extreme
Apr14Extreme
May13Extreme
Jun11Extreme
Jul11Extreme
Aug11Extreme
Sep12Extreme
Oct12Extreme
Nov11Extreme
Dec10Extreme

Air quality in Cayenne 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 Cayenne is worst in February — around 28 µg/m³ PM2.5 (moderate), about 4.0× the cleanest month (August, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateFeb 1627 µg/m³Aug 157 µg/m³
PM2.5 (µg/m³)Level
Jan26Moderate
Feb28Moderate
Mar26Moderate
Apr26Moderate
May21Moderate
Jun12Moderate
Jul8Good
Aug7Good
Sep8Good
Oct10Good
Nov12Good
Dec21Moderate
Location & terrain

Where is Cayenne?

Cayenne sits at 4.9°N, 52.3°W, 7 m above sea level, in French Guiana. The nearest listed city is Rémire-Montjoly, 8.0 km away.

KourouOiapoqueSaint-Laurent-du-Maroni

Topography around Cayenne

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

Within 3 km, the terrain around Cayenne has only modest variations in elevation — a maximum elevation change of 84 m around an average of 4 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 250 m; within 80 km, significant variations in elevation — a maximum elevation change of 487 m.

The land around Cayenne is covered by water (58%) and artificial surfaces (20%) within 3 km, water (55%) and trees (30%) within 16 km, and trees (53%) and water (41%) within 80 km.

3 km
84 m
16 km
250 m
80 km
487 m
treesgrasslandartificial surfaceswaterwetlandmangroves
September weather nearby: Rémire-Montjoly 8.0 km · Matoury 10 km · Kourou 42 km · Oiapoque 134 km · Saint-Laurent-du-Maroni 198 km · Blauwgrond 324 km · Rainville 326 km · Beekhuizen 329 km

French Guiana travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / E
220 V · 50 Hz

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 Cayenne (4.9381°, -52.3346°, 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).