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September Weather in Lisbon, United States

Last updated: June 24, 2025

In September, the average temperature in Lisbon, United States is a pleasant 19°C (67°F). Expect a range where the minimum dips to 4°C (40°F) and the maximum can reach 34°C (93°F). Rain is likely, with an average precipitation of 114 mm (4.5 in) spread over 9 days. You'll also experience a relatively high average humidity of 77%, making it feel quite comfortable.

September Temperature in Lisbon

In September in Lisbon, the average temperature is 19°C (67°F). Maximum temperatures can reach 34°C (93°F), while minimums can drop to as low as 4°C (40°F). Travelers should prepare for a wide range of temperatures and pack accordingly.

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

The chart illustrates September temperature patterns in Lisbon, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Lisbon, September typically has an average temperature of 19°C (67°F), with highs reaching up to 34°C (93°F) and lows dropping to around 4°C (40°F).
JanFebMarAprMayJunJulAugSepOctNovDec303340506270747267564135
Data source: Temperature data for Lisbon generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Lisbon

In Lisbon in September, the precipitation amount is 114 mm (4.5 in) over the course of 9 days.

September Precipitation Trends in Lisbon

The chart displays monthly precipitation patterns in Lisbon, 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 Lisbon, September typically receives around 114 mm (4.5 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec91106101132130131133991151169496
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Lisbon

In Lisbon in September, humidity is 77%. With an average temperature of 19°C (67°F), this humidity feels like a warm embrace, making travel slightly more challenging as the air clings to your skin, turning every step into a leisurely stroll through a sauna.

September Average Humidity in Lisbon

This chart illustrates the average monthly humidity levels in Lisbon, 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 Lisbon is approximately 77%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%88%87%87%81%83%82%76%77%82%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Lisbon

In Lisbon in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Lisbon.

Maximum UV Index Levels in Lisbon for September

The chart shows the monthly maximum UV Index (UVI) for Lisbon 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 Lisbon typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
Data source: Lisbon 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 Lisbon Compares to Other Months

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

This table compares monthly weather conditions in Lisbon, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (30°F)91 mm (3.6 inches)88%moderate
February Weather1°C (34°F)106 mm (4.2 inches)88%moderate
March Weather5°C (41°F)101 mm (4.0 inches)87%high
April Weather10°C (51°F)132 mm (5.2 inches)87%very high
May Weather16°C (62°F)130 mm (5.1 inches)81%very high
June Weather21°C (70°F)131 mm (5.2 inches)83%very high
July Weather24°C (75°F)133 mm (5.2 inches)82%very high
August Weather22°C (72°F)98 mm (3.9 inches)76%very high
September Weather19°C (67°F)114 mm (4.5 inches)77%very high
October Weather14°C (57°F)116 mm (4.6 inches)82%high
November Weather5°C (41°F)94 mm (3.7 inches)89%moderate
December Weather2°C (35°F)95 mm (3.8 inches)86%low

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