September Weather in Porto, Brazil

Last updated: August 22, 2025

In September, the average temperature in Porto, Brazil reaches a warm 30°C (86°F), with a minimum of 20°C (68°F) and a maximum soaring to 39°C (102°F). Expect minimal rainfall, averaging just 2 mm (0.1 in) over 0 days, and enjoy comfortably low humidity levels at 36%.

September Temperature in Porto

In September, in Porto, the average temperature is 30°C (86°F), with maximums reaching up to 39°C (102°F) and minimums dipping as low as 20°C (68°F). Travelers should be prepared for warm weather, so pack light clothing and stay hydrated to make the most of your visit!

September Weather in Porto: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Porto, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Porto, September typically has an average temperature of 30°C (86°F), with highs reaching up to 39°C (102°F) and lows dropping to around 20°C (68°F).

Data source: Temperature data for Porto generated using information from the Copernicus Climate Change Service.

September Precipitation in Porto

In Porto in September, the precipitation amount is 2 mm (0.1 in) during a span of 0 days.

September Precipitation Trends in Porto

The chart displays monthly precipitation patterns in Porto, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Porto, September typically receives around 2 mm (0.1 inches) of precipitation spread over approximately 0 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Porto

In Porto in September humidity is 36%. With an average temperature of 30°C (86°F), this humidity feels like a warm and comfortable embrace, making it enjoyable for exploring the local sights and indulging in outdoor activities.

September Average Humidity in Porto

This chart illustrates the average monthly humidity levels in Porto, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Porto is approximately 36%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Porto

In Porto in September, the maximum UV index reaches 13, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's crucial to take protective measures. For detailed information, you can check the Hourly UV Index in Porto.

Maximum UV Index Levels in Porto for September

The chart shows the monthly maximum UV Index (UVI) for Porto in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Porto typically reaches 13, which falls under the extreme exposure category.

Data source: Porto September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How September Weather in Porto Compares to Other Months

Weather in Porto varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Porto, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Porto, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	28°C (82°F)	194 mm (7.6 inches)	90%	extreme
February Weather	27°C (81°F)	315 mm (12.4 inches)	91%	extreme
March Weather	27°C (80°F)	409 mm (16.1 inches)	92%	extreme
April Weather	27°C (81°F)	312 mm (12.3 inches)	93%	extreme
May Weather	27°C (81°F)	149 mm (5.9 inches)	88%	extreme
June Weather	28°C (82°F)	22 mm (0.9 inches)	75%	extreme
July Weather	28°C (82°F)	18 mm (0.7 inches)	52%	extreme
August Weather	29°C (84°F)	3 mm (0.1 inches)	42%	extreme
September Weather	30°C (86°F)	2 mm (0.1 inches)	36%	extreme
October Weather	30°C (87°F)	7 mm (0.3 inches)	35%	extreme
November Weather	30°C (86°F)	61 mm (2.4 inches)	43%	extreme
December Weather	29°C (85°F)	69 mm (2.7 inches)	76%	extreme