The highest day temperature in September 2025 was 86°F. The lowest night temperature was 49°F. The average values for day and night temperatures during September were 72.0°F и 59.2°F respectivly.

The average sea surface temperature in September 2025 for Porto Alegre was 65.8°F. The maximum and minimum values were 63.8°F and 67.6°F respectively.

You can expect various weather conditions during September. Be ready for sunny, cloudy or even gloomy days.

Precipitation total in September for Porto Alegre is 2.9 in. It makes september the most rainy month of the year.

The average wind speed in September is 6.3 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Porto Alegre in September is 6.3 hours.