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September Weather in Mercer, United States

Last updated: June 24, 2025

In September, the average temperature in Mercer, United States hovers around 14°C (58°F). Expect a temperature range where the minimum dips to -2°C (29°F) and the maximum can reach a warm 31°C (87°F). With an average humidity of 73% and 98 mm (3.9 in) of precipitation spread over 13 days, be prepared for a mix of weather conditions!

September Temperature in Mercer

In September, in Mercer, the average temperature is 14°C (58°F). The maximum can reach 31°C (87°F), while the minimum can dip as low as -2°C (29°F). It's advisable to pack a variety of clothing to accommodate the range of temperatures when traveling during this time.

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 14°C (58°F), with highs reaching up to 31°C (87°F) and lows dropping to around -2°C (29°F).
JanFebMarAprMayJunJulAugSepOctNovDec141427375465696558442920
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 precipitation amount is 98 mm (3.9 in) over a span of 13 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 98 mm (3.9 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec36515392100121110126981185871
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 73%. With an average temperature of 14°C (58°F), this humidity feels like a warm, damp blanket wrapping around you, making outdoor activities a bit uncomfortable for traveling unless you stay hydrated and take frequent breaks in the shade.

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 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%93%89%85%76%71%70%71%73%82%88%91%
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 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 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 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2457810987532
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-10°C (14°F)36 mm (1.4 inches)93%low
February Weather-10°C (14°F)51 mm (2.0 inches)93%moderate
March Weather-3°C (27°F)53 mm (2.1 inches)89%moderate
April Weather3°C (37°F)92 mm (3.6 inches)85%high
May Weather12°C (54°F)100 mm (3.9 inches)76%very high
June Weather18°C (65°F)121 mm (4.8 inches)71%very high
July Weather20°C (69°F)110 mm (4.3 inches)70%very high
August Weather18°C (65°F)126 mm (5.0 inches)71%very high
September Weather14°C (58°F)98 mm (3.9 inches)73%high
October Weather7°C (44°F)118 mm (4.7 inches)81%moderate
November Weather-2°C (29°F)58 mm (2.3 inches)87%moderate
December Weather-7°C (20°F)70 mm (2.8 inches)91%low

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