Devil's Island Weather Guide: Climate & Seasonal Trends

The Tropical Reality of Devil's Island

Devil’s Island (Île du Diable), located 11 kilometers off the coast of French Guiana, experiences a tropical monsoon climate. For travelers, this means year-round high temperatures, intense humidity, and significant rainfall. The weather is defined by the shifting position of the Intertropical Convergence Zone (ITCZ), which dictates the island's distinct wet and dry seasons.

Daily Climate Progression

In this equatorial environment, the weather follows a remarkably consistent daily rhythm:

• Morning: The day usually begins with clear skies or soft light. Temperatures rise rapidly after sunrise, moving from overnight lows of 74°F (23°C) toward the daytime peak.
• Midday and Afternoon: Highs reach approximately 86°F to 91°F (30°C to 33°C). During the wet season, the humidity—often exceeding 80%—makes the "feels like" temperature significantly higher. Afternoon thunderstorms are common, often appearing suddenly as heavy downpours that provide brief relief from the heat.
• Evening and Night: As the sun sets, the atmosphere remains thick. While coastal trade winds (alizés) offer a cooling effect, the temperature rarely dips below 72°F (22°C).

Seasonal Trends

Rather than distinct temperature changes, the seasons on Devil's Island are defined by the volume of water falling from the sky.

The Dry Season (August to November)

This is the most stable period for visiting. Rainfall is at its lowest, particularly in September and October. While still hot, the air is slightly less saturated, and the sun shines for 7–8 hours a day. The trade winds are most consistent during these months, making the heat feel less oppressive.

The Wet Season (December to July)

The long rainy season is characterized by persistent, heavy precipitation.

• The "Little Rain" (December–February): Short, intense showers punctuated by sunny intervals.
• The "Grand Rain" (April–July): The wettest period, peaking in May. During this time, it may rain every day, and the island becomes lush and vibrant. Moisture levels are at their maximum, and the air feels exceptionally heavy.

The "Little Summer" (March)

A brief, unreliable dry spell often occurs in March. Known as the petit été de mars, it provides a week or two of reprieve from the rains before the ITCZ moves back over the region.

Microclimates and Coastal Effects

Being an island gives Devil's Island a distinct advantage over the mainland city of Cayenne. The maritime influence means that while the mainland may suffer from stagnant, sweltering heat, the island receives constant ocean breezes. These winds are crucial for comfort, as they help mitigate the high humidity that would otherwise make physical activity difficult.

Historical Context and Local Experience

Historically, the climate was a weapon of the penal system. For the prisoners of the 19th and early 20th centuries, the sweltering heat and relentless humidity were primary causes of tropical diseases like malaria and yellow fever.

Today, locals and tour operators in Kourou treat the weather with deep respect. They monitor the sea conditions closely, as the Atlantic waters surrounding the Salvation Islands (Îles du Salut) can become choppy during the rainy season or when northern depressions send swells down from the Caribbean. Locals generally advise morning departures to the island to avoid the unpredictable sea states and heavy rains that often develop by late afternoon.

Unique Weather Phenomena

• Sahara Dust: Between January and March, the wind can carry fine dust particles all the way from the Sahara Desert across the Atlantic, creating a hazy horizon and vivid red sunsets.
• Equatorial Rain: The rain here is not a drizzle; it is a "wall of water." These downpours are so dense they can reduce visibility to near zero in seconds, a phenomenon that adds a haunting atmosphere to the island's stone ruins.