Cayenne (French Guiana) weather in September

September in Cayenne: sweltering, a little rain, with clean air — fine if you can take 37°C afternoons.

Updated September 2026 · climate normals from ERA5 reanalysis

Cayenne French Guiana · Guianas & Northern Brazil · City73
  1. 60Jan
  2. 57Feb
  3. 63Mar
  4. 50Apr
  5. 49May
  6. 52Jun
  7. 58Jul
  8. 69Aug
  9. 73Sep
  10. 72Oct
  11. 63Nov
  12. 53Dec

#1 of 12 months in Cayenne · #894 of 1413 destinations to visit in September · comfort 73/100 (tier B)

Days
32°C
Nights
25°C
Wet days
11
Sun
10.9 h
Humidity
77%
Daylight
12 h
Cayenne, French Guiana
Photo: Wilfried · Pexels

Traveller notes on Cayenne in September

Forum posters describe French Guiana's climate in blunt terms - extremely hot and humid - though one visitor specifically compared it favorably to a Florida summer, finding it not quite as bad as expected. Posters describe nearby Devil's Island as a fascinating historical site despite the genuinely intense heat and humidity on site. Posters note at least one trip specifically planned for the August-September stretch, paired with neighboring Suriname and Guyana, suggesting this window is a workable time for a wider Guianas itinerary. Given the limited detailed trip reports available for Cayenne specifically, posters generally describe France's infrastructure standards - European-caliber hotels, restaurants and medical care - as a real practical upside for visitors regardless of exactly which month they choose.
Tripadvisor community · September · 1 month ago · Read more on Tripadvisor ↗

Other months in Cayenne

Forum posters visiting Cayenne describe French Guiana as consistently hot and humid, though several are careful to note it wasn't as brutal as a Florida summer despite the tropical setting. One reviewer visiting Devil's Island specifically called the historical site fascinating but genuinely hot and humid, a pattern posters describe as fairly constant across the destination rather than tied to any one month. Given the limited destination-specific detail for March exactly, this note leans on French Guiana's broader equatorial pattern: March sits within the wetter half of the year here, with substantial rainfall and high humidity typical of this stretch of the northern South American coast. Posters generally rate March as hot, humid and genuinely wet for Cayenne, in line with the destination's consistently tropical character.
Tripadvisor community · March · 1 month ago · Read more on Tripadvisor ↗

Add your own note from Cayenne's card on the map.

Cayenne climate normals — September

Daytime high32°C / 89°F🔥 sweltering
Nighttime low25°C / 76°F
Feels like (high)37°C / 99°F
Sea temperature31°C / 87°F♨️ bath-warm
Rainfall63 mm / 2.5 in🌦 some rain
Rainy days11 days
Humidity77%💦 very humid
Dew point23°C / 73°F
Sunshine10.9 h/day
Daylight12.1 h
Wind15 km/h / 9 mph
Air quality (US AQI)27🍃 good

Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.

Crowds in Cayenne in September

How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.

Busyschool holidays in 2 of the markets that fill it, one of its best months for weather(estimated)

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Peak crowdsBusyShoulder seasonQuiet

Best months for Cayenne's weather

Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).

Best weatherCayenne's weather peaks August–October, best around September.

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Best weatherFair weatherToughest weather

What's on in Cayenne in September

Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.

  • Season

    The long dry season

    15 Aug – 15 Nov · usually

    The most settled months, when forest trails dry out and the rivers up to Amerindian and Maroon villages are easier going. The best window for the Iles du Salut and inland trips, though turtle nesting is over by then.

What's on around the world in September →

Where is Cayenne?

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Cayenne in September — FAQ

Is September a good time to visit Cayenne?
September in Cayenne: sweltering, a little rain, with clean air — fine if you can take 37°C afternoons. It ranks #1 of 12 months for Cayenne on SeasonMap's comfort score (73/100).
What is the weather like in Cayenne in September?
In September, Cayenne averages a daily high of 31.8°C and a low of 24.5°C, with about 62.5 mm of rain over roughly 10.5 rainy days.
What is the air quality in Cayenne in September?
Cayenne has a mean US Air Quality Index of about 27 in September.