Rio das Ostras climate

Name: Rio das Ostras
Address: BR

Rio das Ostras is warmest in February, with average highs of 30 °C, and coldest in July, when nights average 18 °C. December is the wettest month (209 mm) and July the driest (31 mm). Figures are 1991–2020 climate normals.

Across a full year Rio das Ostras averages 1,326 mm of rain and 251 days above 25 °C.

Brazil · population 168,099 · 1991–2020 normals

Temperature below 0 °C to above 30 °C Rain band height is that month’s share of the wettest month

Warmest month February 30 °C
Coldest month July 18 °C
Driest month July 31 mm
Wettest month December 209 mm
Least cloud July 42 % cloud
Hottest on record October 37 °C
Coldest on record July 10 °C
Warmest sea March 25 °C

What to expectRio das Ostras through the year

Rio das Ostras has a clear annual cycle: average daily highs run from 25 °C in July to 30 °C in February, a swing of 5.6 °C in mean temperature across the year.

Counted across a normal year, 251 days a year reach 25 °C, 73 of them reach 30 °C. The warmest reading in the 1991–2020 record is 37 °C, in October.

Rain is strongly seasonal. December averages 209 mm against 31 mm in July — 6.8 times as much. Planning around the dry months matters more here than planning around temperature.

The sea off Rio das Ostras is warmest in March at 25 °C and coldest in September at 21 °C. Sea temperature lags the air by a month or two, which is why late summer swims warmer than early summer at the same air temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	29.4 °C	199 mm	68 %
February	29.9 °C	132 mm	59 %
March	28.7 °C	171 mm	63 %
April	27.3 °C	84 mm	52 %
May	25.3 °C	64 mm	49 %
June	24.8 °C	33 mm	43 %
July	24.5 °C	31 mm	42 %
August	25.0 °C	34 mm	43 %
September	25.8 °C	71 mm	55 %
October	26.7 °C	105 mm	66 %
November	26.9 °C	192 mm	73 %
December	28.4 °C	209 mm	70 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C
January	29.4 °C	23.2 °C	25.9 °C	36.4 °C	19.1 °C	29	14
February	29.9 °C	23.4 °C	26.1 °C	36.0 °C	18.8 °C	27	14
March	28.7 °C	22.8 °C	25.3 °C	36.4 °C	18.6 °C	29	9
April	27.3 °C	21.4 °C	24.0 °C	34.4 °C	15.8 °C	24	5
May	25.3 °C	19.1 °C	21.8 °C	33.6 °C	13.3 °C	15	1
June	24.8 °C	18.0 °C	21.0 °C	31.4 °C	10.6 °C	14	0
July	24.5 °C	17.5 °C	20.5 °C	33.0 °C	10.1 °C	14	1
August	25.0 °C	17.9 °C	20.9 °C	33.2 °C	13.0 °C	15	2
September	25.8 °C	19.0 °C	21.8 °C	36.4 °C	13.3 °C	16	4
October	26.7 °C	20.3 °C	22.9 °C	36.9 °C	14.6 °C	20	6
November	26.9 °C	21.1 °C	23.6 °C	36.2 °C	15.1 °C	20	6
December	28.4 °C	22.5 °C	25.0 °C	35.6 °C	16.2 °C	27	10

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind	Sea temp
January	199 mm	16	13 h/day	68 %	82 %	16 km/h	23.8 °C
February	132 mm	12	13 h/day	59 %	81 %	17 km/h	24.1 °C
March	171 mm	18	12 h/day	63 %	83 %	14 km/h	24.9 °C
April	84 mm	12	12 h/day	52 %	82 %	14 km/h	24.8 °C
May	64 mm	9	11 h/day	49 %	82 %	14 km/h	23.7 °C
June	33 mm	6	11 h/day	43 %	81 %	14 km/h	22.8 °C
July	31 mm	5	11 h/day	42 %	79 %	16 km/h	22.1 °C
August	34 mm	6	11 h/day	43 %	78 %	18 km/h	21.5 °C
September	71 mm	10	12 h/day	55 %	78 %	19 km/h	21.3 °C
October	105 mm	12	13 h/day	66 %	80 %	19 km/h	21.7 °C
November	192 mm	17	13 h/day	73 %	82 %	18 km/h	22.4 °C
December	209 mm	18	14 h/day	70 %	83 %	16 km/h	23.6 °C

How Rio das Ostras compares

The same four figures for nearby destinations, so the numbers above have something to be read against. Summer high is the warmest month's average high; winter low is the coldest month's average low.

Destination	Summer high	Winter low	Rain per year	Days above 25 °C
Rio das Ostras	30 °C	18 °C	1,326 mm	251
Macaé · Brazil	30 °C	18 °C	1,170 mm	243
Cabo Frio · Brazil	28 °C	19 °C	1,239 mm	203
Nova Friburgo · Brazil	27 °C	13 °C	2,042 mm	157
Itaboraí · Brazil	31 °C	16 °C	1,630 mm	253
Campos dos Goytacazes · Brazil	31 °C	18 °C	1,087 mm	289
Teresópolis · Brazil	26 °C	13 °C	2,028 mm	127

Planning a trip? See the best time to visit Rio das Ostras.

QuestionsCommon questions about Rio das Ostras’s climate

When is the best time to visit Rio das Ostras?

That depends on what you want, so the honest answer is a comparison rather than a single month. June, July, August sit closest to 20 °C on average, February is the warmest month and July the driest. The month-by-month table above has the full picture.

How hot does Rio das Ostras get?

In February, the warmest month, daily highs average 30 °C. About 73 days a year pass 30 °C. The highest value in the 1991–2020 record is 37 °C.

How cold does it get in winter?

Nights average 18 °C in July, the coldest month. Freezing nights are not part of a normal year here.

Which month is wettest in Rio das Ostras?

December, averaging 209 mm over 18 days with rain. The driest month is July with 31 mm. The year as a whole averages 1,326 mm.

Are these figures a forecast?

No. They are 1991–2020 climate normals: the average of thirty years, which describes what a month is usually like in Rio das Ostras rather than what any particular week will bring. Individual years can differ substantially from the normal.

Data sources and method

ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
Open-Meteo — Open-Meteo.com. CC BY 4.0
NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
GeoNames — GeoNames.org. CC BY 4.0

Normal period: 1991–2020
Data point: -22.527°, -41.945° (the coordinates the reanalysis values are taken for)
Dataset version: era5-1991-2020-scores1.1
Last processed: 1 August 2026

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: monthly rankings, daylight hours, beach and comfort scores. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.