Weather in Porto Alegre in September 2025
Average weather
Average temperature in Porto Alegre in September
Going from a maximum of +35°C during the day to a minimum of +10°C during the night, the temperature in September averages around +23°C.
The average maximum temperature goes down 16% by the end of the month, compared with the beginning of the month, from +24°C to +20°C.
Is Porto Alegre warm or cold in September?
Porto Alegre is typically mild in September.
Maximum temperatures go up compared to the previous month from +21°C to +21°C. The minimum temperature also goes up from +12°C to +13°C.
Pack a light jacket as it will be warm in the day and cool in the evenings.
Take a look at how September is compared to other months in Porto Alegre:
Climate in Porto Alegre in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +21°C | +21°C | +24°C | ||||
| Min. temperature | ||||||
| +1°C | +4°C | +7°C | ||||
| Max. temperature | ||||||
| +35°C | +36°C | +39°C | ||||
| Rainfall | ||||||
| 118 mm | 153 mm | 152 mm | ||||
| Wind | ||||||
| 2 m/s | 2 m/s | 3 m/s | ||||
| Humidity | ||||||
| 81% | 81% | 79% | ||||
| Air pressure | ||||||
| 1018 HPa | 1016 HPa | 1014 HPa | ||||
| Sunny days | ||||||
| 9 | 7 | 7 | ||||
| Cloudy days | ||||||
| 9 | 8 | 7 | ||||
| Rainy days | ||||||
| 12 | 13 | 15 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September weather is still as ok as in August. The temperature levels stay the same in the area of +21°C for average maximum temperature during the day. Prepare for more rain. Average rainfall goes from 118 mm to 153 mm. Humidity levels don’t change as the month goes on, averaging around 81%. The average wind speed doesn’t change much during September, staying around 2 m/s. The days becoming less sunny, going from 9 sunny days in August to 7 in September.
October brings much the same weather, it remains ok.
Wind
The average wind speed is 3 m/s getting up to 8 m/s which is a medium breeze. You can feel it, especially getting out of the water.
The average wind speed in Porto Alegre is gradually increasing during September, going from 3 m/s to 3 m/s over the course of the month.
Rain
How was the weather last September in Porto Alegre?
Climate Change over Years
The climate in Porto Alegre in September has not changed much over the last 43 years.
The average temperature was the lowest in 1983 (+23°C) and the highest in 2012 (+26°C). The driest year was 2004 with only 1129 mm of rainfall, and the wettest year was 1998 with 2041 mm.
FAQ
Is September a good time to visit Porto Alegre?
Can you sunbathe in Porto Alegre in September?
Is Porto Alegre rainy in September?
Is it sunny in Porto Alegre in September?
Other cities in Brazil
Monthly weather in Porto Alegre
Source of the data
For this page, we’ve looked at the typical weather in Porto Alegre, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.