Weather in Rio de Janeiro in December

Shoulder season. December is shoulder season in Rio de Janeiro — cheaper, quieter, and a genuine gamble. You should expect rain on 20 days of the month, which is more days wet than dry.

December ranks 11 of 12 — near the bottom of Rio de Janeiro's year. July is the month that works, and the swing between the two is 36 points, which is a different holiday rather than a slightly better one.

Rain on 20 of the month's 31 days, 7 of them heavy. At that frequency a wet-weather backup is not a contingency, it is the itinerary — book the indoor things first and treat the clear days as the bonus. Natural fibres and a second shirt for the day. At 84% nothing dries, including you.

What the averages hide

Averages flatten a month, and this one hides a few things: 8 days top 30 °C — hot spells arrive, but they break; the day barely swings — 5.1 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest December day reached 36.7 °C and the coldest night fell to 19.1 °C, and the wettest single day dropped 88 mm — roughly 38% of the month's rain in one day.

December is moderately variable: 71 mm in the driest year against 648 mm in the wettest, around an average of 232 mm. Roughly two Decembers in three land near that average, and the third does something else entirely.

Wind is light at 8.9 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 84%, high enough to notice on the warm days without dominating them.

How December sits in the year

Temperatures hold steady either side: 27 °C in November, 28.1 here, 29 in January. Nothing about the timing within the month matters much.

Daylight in December

December is at or near the longest days of Rio de Janeiro's year: 13.5 hours of daylight, holding steady all month. Evenings are the real gain — dinner outdoors still happens in full light.

Sea temperature

The sea sits at about 25.1 °C in December — warm enough to stay in as long as you like. The sea peaks at 26.7 °C in March and bottoms out at 22.3 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Quiet. Few other visitors, cheaper rooms, and a real chance some seasonal operators are shut.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

December in Rio de Janeiro versus nearby

If Rio de Janeiro is one option among several, the nearby comparison is worth making. Belo Horizonte is close enough to be a coin toss — within a degree on temperature, 4 days more rain. São Paulo is close enough to be a coin toss — within a degree on temperature, 2 days more rain.

So: December is a compromise. July is 33 points better and is what Rio de Janeiro is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Rio de Janeiro

See all twelve months in Rio de Janeiro, or where else to go in December.