The highest day temperature in December 2025 was 96°F. The lowest night temperature was 70°F. The average values for day and night temperatures during December were 86.6°F и 76.9°F respectivly.

The average sea surface temperature in December 2025 for Niteroi was 81.4°F. The maximum and minimum values were 79.0°F and 84.2°F respectively.

Most of the days in December are gloomy but you can also expect sunny days.

Precipitation total in December for Niteroi is 2.3 in. It makes december one of the most rainy months of the year.

The average wind speed in December is 5.6 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Niteroi in December is 6.3 hours.