December weather forecast
Grand Usine, French Guiana

The first month of the winter, December, is also a hot month in Grand Usine, French Guiana, with an average temperature ranging between max 30.8°C (87.4°F) and min 20.9°C (69.6°F).

Temperature

The transition to December results in a modest reduction in average high-temperature, moving from 34°C (93.2°F) in November to a still tropical 30.8°C (87.4°F). Grand Usine's nights in December experience an average temperature drop to an agreeable 20.9°C (69.6°F).

Heat index

December's heat index is computed to be an extremely hot 42°C (107.6°F). Incorporate extra safety measures to avoid heat exhaustion and heat cramps. Continuous activity could provoke heatstroke.
Given the heat index, its values are aligned with shaded sites and gentle winds. When under direct sunshine, the heat index may be elevated by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'feels like', marries air temperature and humidity to produce a value illustrating perceived warmth. This impact is subjective, influenced by the person's physical activity and individual heat perception, affected by factors including wind, attire, and metabolic differences. Should you be directly under the sun, anticipate a possible increase in the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely significant for babies and toddlers. Children often fail to recognize the requirement to rest and rehydrate. Thirst, being a late symptom of dehydration, underlines the importance of maintaining hydration, especially during ongoing physical activities.
When the body gets too warm, it perspires, leading to sweat evaporation which cools it down. During high air temperature and humidity (high heat index), the process of perspiration is hindered, intensifying the sensation of heat. Overheating risks increase with rising body temperatures, especially if heat release isn't efficient.

Humidity

In December, the average relative humidity is 85%.

Rainfall

In Grand Usine, in December, during 26.2 rainfall days, 112mm (4.41") of precipitation is typically accumulated. Throughout the year, there are 265.5 rainfall days, and 1078mm (42.44") of precipitation is accumulated.

Daylight

December has the shortest days of the year, with an average of 11h and 54min of daylight.
On the first day of December, sunrise is at 06:22 and sunset at 18:19. On the last day of the month, sunrise is at 06:36 and sunset at 18:32 -03.

Sunshine

In Grand Usine, the average sunshine in December is 5.6h.

UV index

The months with the lowest UV index are January, March and December, with an average maximum UV index of 5. A UV Index of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for average individuals.
Note: A maximum UV index of 5 in December translates into the following recommendations:
Be vigilant - Preventing sunburn is recommended. Being exposed to the midday Sun can have harmful effects due to strong UV radiation; always take precautions. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.