Cayenne, the capital of French Guiana, is defined by an equatorial tropical rainforest climate. Its weather is characterized by remarkable thermal stability, high relative humidity near 85%, and distinct rainy and dry seasons that dictate the rhythm of life on the edge of the Amazon. Unlike temperate zones, seasons in Cayenne are differentiated by precipitation and wind rather than temperature shifts.
Seasonal Trends: The Four Phases
Cayenne experiences four distinct periods of varying intensity, shaped by the migration of the Intertropical Convergence Zone (ITCZ):
- The Long Rainy Season (April to July): This is the wettest time of year, peaking in May. Rainfall is monumental, often exceeding 500mm (20 inches) in a single month. During this period, the sky is frequently overcast, and the ground remains saturated as daily downpours occur with monsoon-level intensity.
- The Long Dry Season (August to November): This is the sunniest and hottest time of year. Rainfall drops significantly, reaching its lowest in September and October. While it is "dry" by tropical standards, sporadic showers still occur. The trade winds (Alizés) are weaker during this time, making the heat feel more stationary.
- The Short Rainy Season (December to January): Also known as the petit carême de Noël, this period sees the return of frequent showers, though they are generally less intense and persistent than those in the major rainy season.
- The Little Summer of March (February to Mid-March): A meteorological curiosity known locally as le petit été de mars. During these weeks, the rains suddenly slacken and the sun returns for a brief "intermission," providing a dry window in the middle of the wet half of the year.
Daily Rhythms and the "Feel" of the Air
The daily cycle in Cayenne is predictable. Mornings often begin with high humidity and mist if it rained during the night. As the sun rises, the temperature climbs quickly to around 30°C (86°F), but the high humidity levels make the