December weather forecast
Rio de Janeiro, Brazil

To conclude the year, December brings about summer in full swing in Rio de Janeiro. An impressive peak in rainfall to 98mm (3.86") signifies the commencement of the wet season. Regardless of the showers, temperatures pace up to 28.2°C (82.8°F), radiating the summer warmth that people yearn for in a tropical city. This weather fully ushers in beach season, even with occasional splash of rain. Amid the holiday season, the city lights up, enhancing its allure amid the balmy December weather.

Temperature

December's presence records an average high-temperature of a still moderately hot 28.2°C (82.8°F), closely mirroring November's climate. Rio de Janeiro throughout December, records an average low-temperature of 23°C (73.4°F).

Heat index

In December, the average heat index is estimated at a hot 33°C (91.4°F). Exercise increased caution, heat cramps and heat exhaustion are potential hazards. Continuous activity could lead to heatstroke.
Heat index guidelines indicate values are for light wind scenarios and shaded regions. The heat index could experience an increase of 15 Fahrenheit (8 Celsius) degrees due to direct sunlight.
Note: The heat index, also known as 'apparent temperature' or 'feels like', evaluates the perceived heat by adding the effect of moisture in the air. The influence of weather is personal, differing among individuals based on variations in body mass, stature, and the degree of physical exertion. The sun, when shining directly, can have a significant impact on the perceived temperature, increasing the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Young individuals are typically more threatened than adults due to their reduced perspiration. Also, the larger skin surface proportionate to their small bodies and the increased heat from their activities magnify their risk.

Humidity

In December, the average relative humidity is 81%.

Rainfall

In Rio de Janeiro, in December, during 21.9 rainfall days, 98mm (3.86") of precipitation is typically accumulated. Throughout the year, in Rio de Janeiro, Brazil, there are 192.5 rainfall days, and 812mm (31.97") of precipitation is accumulated.

Sea temperature

In December, the average sea temperature is 24°C (75.2°F).
Note: Every individual's cold threshold differs, but factors like today's sunshine, wind, and temperature can tip the scales for a delightful swim in 24°C (75.2°F) waters. For reference, Olympians swim in waters of 25°C (77°F) to 28°C (82.4°F).

Daylight

The month with the longest days in Rio de Janeiro is December, with an average of 13h and 30min of daylight.
On the first day of the month, sunrise is at 04:58 and sunset at 18:25. On the last day of December, sunrise is at 05:10 and sunset at 18:41 -03.

Sunshine

In December, the average sunshine in Rio de Janeiro is 8.3h.

UV index

The average daily maximum UV index in December is 6. A UV Index value of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV rays for ordinary individuals.
Note: A daily maximum UV index of 6 in December translates into the following instructions:
Implement precautions and maintain sun safety methods. Avoidance of sunburn is demanded. Between 10 a.m. and 4 p.m., the Sun's UV radiation is at its peak. Limit your exposure to direct sunlight during these hours. Arm yourself against UV rays' harm with protective apparel and UV-filtering shades. Be careful! The Sun's UV radiation is accentuated by reflecting off sand and water.