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September Weather in Petersburg, United States

Last updated: June 24, 2025

In Petersburg, United States, the average temperature in September is a pleasant 21°C (71°F), with minimums dipping to 7°C (45°F) and maximums soaring to 35°C (95°F). Expect 87 mm (3.4 in) of precipitation over about 7 days, while the average humidity hovers around 73%.

September Temperature in Petersburg

In September in Petersburg, the average temperature is 21°C (71°F). The maximum can reach 35°C (95°F), while the minimum can drop to as low as 7°C (45°F). This makes Petersburg an ideal destination for travelers looking to enjoy a warm climate with refreshing 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 21°C (71°F), with highs reaching up to 35°C (95°F) and lows dropping to around 7°C (45°F).
JanFebMarAprMayJunJulAugSepOctNovDec333745546673777570594439
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 87 mm (3.4 in) over a span of 7 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 87 mm (3.4 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec8011013512512614611395879893109
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 73%. With an average temperature of 21°C (71°F), this humidity feels like a warm, enveloping blanket that can make outdoor activities a bit uncomfortable, but with proper hydration and breaks in the shade, it’s still manageable for 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 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%88%87%85%81%82%81%73%73%78%89%87%
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 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 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 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098643
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 Weather1°C (34°F)80 mm (3.1 inches)88%moderate
February Weather3°C (38°F)110 mm (4.3 inches)88%moderate
March Weather7°C (46°F)135 mm (5.3 inches)87%high
April Weather12°C (55°F)125 mm (4.9 inches)85%very high
May Weather19°C (66°F)126 mm (4.9 inches)81%very high
June Weather23°C (74°F)146 mm (5.7 inches)82%very high
July Weather25°C (78°F)113 mm (4.5 inches)81%very high
August Weather24°C (75°F)95 mm (3.7 inches)73%very high
September Weather21°C (71°F)87 mm (3.4 inches)73%very high
October Weather15°C (59°F)98 mm (3.9 inches)78%high
November Weather7°C (44°F)93 mm (3.7 inches)89%moderate
December Weather4°C (39°F)109 mm (4.3 inches)87%moderate

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