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September Weather in Mercer, United States

Last updated: June 24, 2025

In Mercer, United States, the average temperature in September is a pleasant 19°C (66°F). Expect a minimum dip to 3°C (38°F) and a maximum peak of 33°C (91°F). During this month, you'll experience 113 mm (4.4 in) of precipitation spread over about 10 days, contributing to an average humidity level of 77%.

September Temperature in Mercer

In September in Mercer, the average temperature is 19°C (66°F). Maximum temperatures can reach 33°C (91°F), while minimums can drop as low as 3°C (38°F). This climate makes Mercer an ideal destination for travelers seeking a mix of warm and cool experiences.

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

The chart illustrates September temperature patterns in Mercer, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Mercer, September typically has an average temperature of 19°C (66°F), with highs reaching up to 33°C (91°F) and lows dropping to around 3°C (38°F).
JanFebMarAprMayJunJulAugSepOctNovDec283138486068737165554034
Data source: Temperature data for Mercer 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 Mercer

In Mercer in September, the total precipitation amount is 113 mm (4.4 in) over a span of 10 days.

September Precipitation Trends in Mercer

The chart displays monthly precipitation patterns in Mercer, 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 Mercer, September typically receives around 113 mm (4.4 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec101110115144149140146105113127109106
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Mercer

In Mercer in September, humidity is 77%. With an average temperature of 19°C (66°F), this humidity feels like a heavy blanket wrapping around you, making the air feel thick and sticky, which can be quite uncomfortable for traveling.

September Average Humidity in Mercer

This chart illustrates the average monthly humidity levels in Mercer, 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 Mercer 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 Mercer

In Mercer 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 Mercer.

Maximum UV Index Levels in Mercer for September

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

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

This table compares monthly weather conditions in Mercer, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (28°F)101 mm (4.0 inches)88%moderate
February Weather0°C (32°F)110 mm (4.3 inches)88%moderate
March Weather4°C (39°F)115 mm (4.5 inches)87%high
April Weather9°C (49°F)144 mm (5.7 inches)87%very high
May Weather16°C (60°F)149 mm (5.9 inches)81%very high
June Weather20°C (68°F)140 mm (5.5 inches)83%very high
July Weather23°C (73°F)146 mm (5.8 inches)82%very high
August Weather21°C (71°F)105 mm (4.1 inches)76%very high
September Weather19°C (66°F)113 mm (4.4 inches)77%very high
October Weather13°C (55°F)127 mm (5.0 inches)82%high
November Weather4°C (40°F)109 mm (4.3 inches)89%moderate
December Weather1°C (34°F)106 mm (4.2 inches)86%low

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