December weather forecast
Porto Velho, Brazil

December, the first month of the summer in Porto Velho, is still a hot month, with an average temperature ranging between min 22.7°C (72.9°F) and max 30.5°C (86.9°F).

Temperature

Porto Velho experiences a transition to a still hot 30.5°C (86.9°F) in average high-temperatures with the arrival of December, not greatly differing from November's 32.3°C (90.1°F). An average nighttime temperature of 22.7°C (72.9°F) is witnessed throughout December.

Heat index

The heat index value for December is estimated at a blisteringly hot 42°C (107.6°F). Implement heightened safety measures - risk of heat exhaustion and heat cramps is increased. Prolonged activity may result in heatstroke.
It is worth noting that heat index values are gauged for conditions in the shade and light breezes. Heat index values might soar by up to 15 Fahrenheit (8 Celsius) degrees with exposure to direct sunshine.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', melds the effects of warmth and moisture to generate a feeling of heat. One's perception of weather can be shaped by other factors, involving metabolic differences, pregnancy, and physical exertion. Direct sun exposure is noteworthy in its ability to escalate the felt temperature, potentially adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values are extremely significant for children. Young kids are often more at risk than adults as they tend to perspire less. Besides, their skin surface is larger relative to their small bodies, and their increased heat output from their active lifestyle compounds their risk.
In high temperatures, perspiration kicks in, allowing the human body to cool down through the evaporation of sweat. Increased relative humidity interferes with body cooling by slowing the rate of evaporation, resulting in a slower body cooling rate and a heightened feeling of heat. When heat uptake goes beyond the body's cooling mechanisms, there's a surge in body temperature, posing health risks.

Humidity

In Porto Velho, the average relative humidity in December is 88%.

Rainfall

In Porto Velho, during December, the rain falls for 29.4 days and regularly aggregates up to 199mm (7.83") of precipitation. Throughout the year, there are 251.1 rainfall days, and 1471mm (57.91") of precipitation is accumulated.

Daylight

The month with the longest days is December, with an average of 12h and 36min of daylight.
On the first day of the month, sunrise is at 05:46 and sunset at 18:22. On the last day of December, sunrise is at 06:00 and sunset at 18:37 -04.

Sunshine

The average sunshine in December in Porto Velho is 6.8h.

UV index

The months with the lowest UV index in Porto Velho are January through April and December, with an average maximum UV index of 6. A UV Index of 6 to 7 symbolizes a high threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: In December, a daily UV index of 6 turns into the following recommendations:
Adhere to precautions and respect sun safety doctrines. Avoiding sunburn is vital. Between 10 a.m. and 4 p.m., UV radiation is strongest. Make an effort to avoid direct sunlight during this time, remembering that shade structures may not provide full sun protection. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses.