December weather forecast
Nilópolis, Brazil

The first month of the summer, December, is also a moderately hot month in Nilópolis, Brazil, with an average temperature fluctuating between 21.3°C (70.3°F) and 29.3°C (84.7°F).

Temperature

The shift into December reveals an average high-temperature of a still moderately hot 29.3°C (84.7°F), closely mirroring November's climate. Nilópolis observes an average low-temperature of 21.3°C (70.3°F) during December.

Heat index

In December, the average heat index is computed to be a very hot 36°C (96.8°F). Ensure heightened precautions, risk of heat cramps and heat exhaustion is significant. Sustained activity could provoke heatstroke.
It is emphasized that the heat index's values are meant for shaded zones with mild winds. An exposure to direct sunlight may lift the heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', quantifies the warmth felt when relative humidity is considered. This effect is personal, influenced by the individual's physical activity and heat sensitivity, shaped by factors including wind, attire, and metabolic variations. In the direct sunlight, the weather's impact can be amplified, possibly boosting the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are primarily vital 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.
Perspiration, which is the evaporation of sweat, is a primary way the human body manages and dispels excessive warmth. In situations of high air temperature combined with high humidity (significant heat index), the body's ability to perspire is reduced, heightening the sense of warmth. Excessive heat that's not properly managed leads to increased body temperatures and resultant health issues.

Humidity

The average relative humidity in December in Nilópolis is 82%.

Rainfall

In Nilópolis, in December, it is raining for 25.7 days, with typically 134mm (5.28") of accumulated precipitation. Throughout the year, there are 220.6 rainfall days, and 991mm (39.02") of precipitation is accumulated.

Daylight

December has the longest days of the year in Nilópolis, with an average of 13h and 30min of daylight.
On the first day of December, sunrise is at 04:59 and sunset at 18:25. On the last day of the month, sunrise is at 05:11 and sunset at 18:42 -03.

Sunshine

In Nilópolis, the average sunshine in December is 7.5h.

UV index

December is the month with the highest UV index, with an average maximum UV index of 7. A UV Index estimate of 6 to 7 represents a high threat to health from exposure to the Sun's UV rays for ordinary individuals.
Note: In December, a daily UV index of 7 turns into the following recommendations:
Shun overexposure. Protection from sun ravages is indispensable. Avoid direct Sun exposure and seek shade from 10 a.m. to 4 p.m., the period of highest UV radiation. Remember, however, that not all shade structures offer full protection. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation.