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September Weather in Petersburg, United States

Last updated: June 24, 2025

In September, the average temperature in Petersburg, United States is 12°C (54°F), with a cozy minimum of 3°C (37°F) and a pleasant maximum reaching 25°C (77°F). Expect a fair share of rain, with 288 mm (11.3 in) of precipitation spread over 18 days. Don't forget, the average humidity hovers around a remarkable 104%!

September Temperature in Petersburg

In September in Petersburg, the average temperature is 12°C (54°F), with maximums reaching 25°C (77°F) and minimums dipping as low as 3°C (37°F). This weather makes it an ideal time for travelers to enjoy outdoor activities while packing a light jacket for cooler evenings.

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

The chart illustrates September temperature patterns in Petersburg, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Petersburg, September typically has an average temperature of 12°C (54°F), with highs reaching up to 25°C (77°F) and lows dropping to around 3°C (37°F).
JanFebMarAprMayJunJulAugSepOctNovDec302935425055595854433732
Data source: Temperature data for Petersburg 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 Petersburg

In Petersburg in September, the precipitation amount is 288 mm (11.3 in) spread over 18 days.

September Precipitation Trends in Petersburg

The chart displays monthly precipitation patterns in Petersburg, 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 Petersburg, September typically receives around 288 mm (11.3 inches) of precipitation spread over approximately 18 days.
JanFebMarAprMayJunJulAugSepOctNovDec225177177190160206195297288276309258
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Petersburg

In Petersburg in September, humidity is 104%. With an average temperature of 12°C (54°F), this humidity feels like an oppressive blanket enveloping you, making every step feel heavier and every breath feel damp, which can dampen the excitement of traveling.

September Average Humidity in Petersburg

This chart illustrates the average monthly humidity levels in Petersburg, 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 Petersburg is approximately 104%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%84%86%88%88%96%110%111%104%96%92%91%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Petersburg

In Petersburg in September, the maximum UV index reaches 5, which corresponds to a moderate Exposure Category. Under these conditions, the estimated time to burn is approximately 30 minutes. For more details, you can check the Hourly UV Index in Petersburg.

Maximum UV Index Levels in Petersburg for September

The chart shows the monthly maximum UV Index (UVI) for Petersburg 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 Petersburg typically reaches 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec123566775311
Data source: Petersburg 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 Petersburg Compares to Other Months

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

This table compares monthly weather conditions in Petersburg, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (30°F)225 mm (8.9 inches)88%low
February Weather-2°C (29°F)176 mm (6.9 inches)84%low
March Weather1°C (35°F)177 mm (7.0 inches)86%moderate
April Weather5°C (42°F)190 mm (7.5 inches)88%moderate
May Weather10°C (50°F)160 mm (6.3 inches)88%high
June Weather13°C (55°F)206 mm (8.1 inches)96%high
July Weather15°C (59°F)195 mm (7.7 inches)110%high
August Weather15°C (59°F)297 mm (11.7 inches)111%high
September Weather12°C (54°F)288 mm (11.3 inches)104%moderate
October Weather6°C (44°F)276 mm (10.9 inches)96%moderate
November Weather3°C (38°F)309 mm (12.2 inches)92%low
December Weather0°C (33°F)258 mm (10.2 inches)91%low

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