Climate averages 1991–2020
Rio das Ostras weather
in December.
A hot, very wet month: the 4th warmest and the wettest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a hot month in Rio das Ostras: daytime highs average 28.4°C and nights cool to about 22.4°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 222 mm of rain on roughly 19 days, which makes December a very wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 13 h 29 min on an average December day.
The nearest other city in this atlas is Macaé (23 km away). In December its highs average 28.0°C, about as warm as Rio das Ostras, with 149 mm of rain.
Among the 448 cities listed in Brazil, Rio das Ostras ranks joint 213th of 448 for the warmest December highs and joint 304th of 448 for the driest December (rainfall, lowest first). The mean December high of those 448 cities is 28.5°C; Rio das Ostras is 0.1°C cooler than that mean.
From December to January, average highs rise by 1.0°C to 29.4°C, and monthly rainfall falls from 222 mm to 206 mm.
The annual picture
December in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Rio das Ostras climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 29.4°C23.2°C | 23.2°C | 206 | 16.5 | 13.313 h |
| February | 29.8°C23.4°C | 23.4°C | 141 | 12.8 | 12.913 h |
| March | 28.6°C22.8°C | 22.8°C | 172 | 17.6 | 12.212 h |
| April | 27.2°C21.3°C | 21.3°C | 85 | 12.1 | 11.612 h |
| May | 25.1°C19.1°C | 19.1°C | 60 | 9.5 | 11.111 h |
| June | 24.7°C17.9°C | 17.9°C | 31 | 5.9 | 10.811 h |
| July | 24.4°C17.4°C | 17.4°C | 29 | 5.6 | 10.911 h |
| August | 25.0°C17.8°C | 17.8°C | 34 | 6.5 | 11.311 h |
| September | 25.7°C18.9°C | 18.9°C | 73 | 10.0 | 11.912 h |
| October | 26.6°C20.2°C | 20.2°C | 108 | 11.9 | 12.613 h |
| November | 26.8°C21.0°C | 21.0°C | 203 | 17.5 | 13.213 h |
| December, selected | 28.4°C22.4°C | 22.4°C | 222 | 19.0 | 13.513 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
December in nearby cities
- Macaé in DecemberBrazil · 23 kmHigh 28.0°C · Low 22.6°C · 149 mm rain
- São Pedro da Aldeia in DecemberBrazil · 38 kmHigh 26.5°C · Low 22.7°C · 142 mm rain
- Cabo Frio in DecemberBrazil · 41 kmHigh 26.5°C · Low 22.9°C · 96 mm rain
- Araruama in DecemberBrazil · 56 kmHigh 26.6°C · Low 22.9°C · 189 mm rain
- Nova Friburgo in DecemberBrazil · 66 kmHigh 26.2°C · Low 19.1°C · 352 mm rain
- Saquarema in DecemberBrazil · 68 kmHigh 27.4°C · Low 22.7°C · 122 mm rain
- Itaboraí in DecemberBrazil · 97 kmHigh 28.7°C · Low 21.6°C · 255 mm rain
- Maricá in DecemberBrazil · 100 kmHigh 29.0°C · Low 23.0°C · 123 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Rio das Ostras) is explained once on the Rio das Ostras year overview and on the Sources, method and limits page.