december hosts the coveted summer solstice, in the southern hemisphere, it is the months with the longest day, which has an average length of 13:32 hours juts two days before christmas - the solar radiation levels during the month are high, as well, so taking care when out in the sun is imperative.

december is a particularly festive time - The warmth of the weather extends to the cariocas, and a flexible schedule is in order, not to miss the many spontaneous public parties and season celebrations.

the amount of visitors received  in rio during christmas holidays is only comparable to carnival attendance, Rio de Janeiro's greatest feast - this link gives access to detailed  daily, weekly, and monthly weather forecasts, as well as sunrise and sunset times.