Weather in Rio de Janeiro in September

How September compares

September is the 8th warmest month of the year in Rio de Janeiro and ranks 70th of 134 destinations we compare for September - see where else is hot in September. Against London's average high of 18.6°C in September, Rio de Janeiro is 7.9°C warmer by day and 7.4°C warmer at night.

Daytime and night-time in September

The typical September day in Rio de Janeiro peaks at 26.5°C, but that is an average: the warmest 10% of days reach 32.3°C or more. About 60% of days top 25°C and 1 in 4 pass 30°C. Nights average 18.6°C; one night in ten drops to 16.3°C or lower, so pack a layer for evenings. Between 1991 and 2020 the hottest September day here reached 39.0°C (2015-09-25) and the coldest night 11.4°C (2006-09-06).

Rain in September

Wet (more than 8 rainy days): about 11 days with 1 mm or more, 88 mm in total. Year to year it varies a lot - the wettest September was 1992 with 193 mm, the driest 2017 with 14 mm. Humidity averages 77%.

Sea temperature in September

The sea averages 21.9°C - bracing (18-22°c). Depending on the year it ranges from 20.8°C to 22.9°C. For the warmest sea here, come in February (26.4°C).

Sunshine and daylight

Around 5.1 hours of sunshine a day (estimated from cloud cover), 11.9 hours of daylight: the sun rises about 05:49 and sets about 17:47 local time in mid-September. Average cloud cover is 57%.

Is September a good time to visit Rio de Janeiro?

It is a reasonable choice: hot days but expect showers. The best months for Rio de Janeiro on our scoring are August, June, July; months averaging 25°C or more: Jan, Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec.

Warm enough for summer clothes, but pack a layer

Rio feels noticeably warmer than London in September, with average daytime highs 7.9°C higher. Days reach 25°C around 60% of the time, so lightweight clothes should earn their place in your suitcase. It is not consistently gentle warmth, though: 23% of days reach 30°C, and humidity of 77% can make walking around feel sticky. Keep strenuous plans flexible and take breaks out of the midday heat when temperatures climb. Evenings are generally milder, but the coldest nights can fall to 16.3°C or below. A light jumper or jacket is therefore useful, especially if you tend to feel chilly after sitting outdoors.

Leave room for rain and cooler swims

September is a wet month, so avoid making every day's plans depend on clear skies. Bring a compact umbrella or light waterproof and have an indoor alternative ready. Rainy-day figures do not tell you when rain will arrive or how long it will last, so there is no basis for assuming it will conveniently pass overnight. Sunshine averages about 5.1 hours within 11.9 hours of daylight: expect some sunshine, not uninterrupted blue skies. The sea averages 21.9°C, which is bracing rather than comfortably warm. That makes September more appealing if swimming is optional; if long, warm-water swims are central to your holiday, the water temperature is a drawback.