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September Weather in Viterbo, Italy

Last updated: August 23, 2025

In September, the average temperature in Viterbo, Italy hovers around 21°C (69°F), providing a pleasant climate for outdoor activities. Daily temperatures can vary, with a minimum of 9°C (48°F) and a maximum reaching up to 31°C (88°F). Expect some rain, as precipitation amounts average 92 mm (3.6 in) over 9 days. Additionally, the air carries a comfortable average humidity of 66%, making it an ideal time to explore the local scenery.

September Temperature in Viterbo

In September in Viterbo, the average temperature is 21°C (69°F), with maximums reaching up to 31°C (88°F) and minimums dropping as low as 9°C (48°F). This diverse temperature range makes it an ideal time to explore all that Viterbo has to offer, whether you prefer warm daytime activities or cooler evening adventures.

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

The chart illustrates September temperature patterns in Viterbo, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Viterbo, September typically has an average temperature of 21°C (69°F), with highs reaching up to 31°C (88°F) and lows dropping to around 9°C (48°F).
JanFebMarAprMayJunJulAugSepOctNovDec434749556372777869615346
Data source: Temperature data for Viterbo 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 Viterbo

In Viterbo in September, the precipitation amount is 92 mm (3.6 in) during 9 days, indicating a relatively wet period for the region.

September Precipitation Trends in Viterbo

The chart displays monthly precipitation patterns in Viterbo, 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 Viterbo, September typically receives around 92 mm (3.6 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec56707574813532309292155110
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Viterbo

In Viterbo in September humidity is 66%. With an average temperature of 21°C (69°F), this humidity feels like a warm embrace, making it a bit sticky, but still comfortable for traveling as long as you stay hydrated and take breaks in the shade.

September Average Humidity in Viterbo

This chart illustrates the average monthly humidity levels in Viterbo, 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 Viterbo is approximately 66%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%76%68%70%69%62%57%55%66%79%84%83%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Viterbo

In Viterbo in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Viterbo.

Maximum UV Index Levels in Viterbo for September

The chart shows the monthly maximum UV Index (UVI) for Viterbo 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 Viterbo typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34578101097532
Data source: Viterbo 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 Viterbo Compares to Other Months

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

This table compares monthly weather conditions in Viterbo, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather6°C (43°F)56 mm (2.2 inches)84%moderate
February Weather8°C (47°F)70 mm (2.7 inches)76%moderate
March Weather10°C (49°F)75 mm (2.9 inches)68%moderate
April Weather13°C (55°F)74 mm (2.9 inches)70%high
May Weather17°C (63°F)81 mm (3.2 inches)69%very high
June Weather22°C (72°F)35 mm (1.4 inches)62%very high
July Weather25°C (77°F)32 mm (1.3 inches)57%very high
August Weather25°C (78°F)30 mm (1.2 inches)55%very high
September Weather21°C (69°F)92 mm (3.6 inches)66%high
October Weather16°C (61°F)92 mm (3.6 inches)79%moderate
November Weather12°C (54°F)155 mm (6.1 inches)84%moderate
December Weather8°C (47°F)110 mm (4.3 inches)83%low

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