September Weather in Mertztown, United States

Last updated: June 24, 2025

In September, the average temperature in Mertztown, United States is a pleasant 20°C (69°F). However, you might experience a chill with minimums as low as 3°C (38°F), while the mercury can rise to a maximum of 34°C (94°F). Prepare for 100 mm (3.9 in) of rainfall spread over 9 days, and be mindful of the average humidity at 66%.

September Temperature in Mertztown

In September in Mertztown, the average temperature is 20°C (69°F). Maximum temperatures can reach 34°C (94°F), while minimum temperatures can drop as low as 3°C (38°F). Overall, this month offers a pleasant climate for travelers, making it an ideal time to explore Mertztown.

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

The chart illustrates September temperature patterns in Mertztown, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Mertztown, September typically has an average temperature of 20°C (69°F), with highs reaching up to 34°C (94°F) and lows dropping to around 3°C (38°F).
JanFebMarAprMayJunJulAugSepOctNovDec333641526371777569584337
Data source: Temperature data for Mertztown 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 Mertztown

In Mertztown in September, the precipitation amount is 100 mm (3.9 in) spread over 9 days.

September Precipitation Trends in Mertztown

The chart displays monthly precipitation patterns in Mertztown, 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 Mertztown, September typically receives around 100 mm (3.9 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec6910610010513210113113510010589101
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Mertztown

In Mertztown in September humidity is 66%. With an average temperature of 20°C (69°F), this humidity feels like a gentle enveloping warmth, making it comfortable for traveling but with a slight stickiness that may encourage you to seek shade or refreshments frequently.

September Average Humidity in Mertztown

This chart illustrates the average monthly humidity levels in Mertztown, 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 Mertztown is approximately 66%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%85%85%83%75%74%65%62%66%79%87%85%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Mertztown

In Mertztown 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 Mertztown.

Maximum UV Index Levels in Mertztown for September

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

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

This table compares monthly weather conditions in Mertztown, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (33°F)69 mm (2.7 inches)87%moderate
February Weather2°C (36°F)106 mm (4.2 inches)85%moderate
March Weather5°C (42°F)100 mm (3.9 inches)85%high
April Weather11°C (52°F)105 mm (4.1 inches)83%very high
May Weather17°C (63°F)132 mm (5.2 inches)75%very high
June Weather22°C (72°F)101 mm (4.0 inches)73%very high
July Weather25°C (78°F)130 mm (5.1 inches)65%very high
August Weather24°C (75°F)135 mm (5.3 inches)62%very high
September Weather20°C (69°F)100 mm (3.9 inches)66%very high
October Weather15°C (59°F)105 mm (4.1 inches)79%high
November Weather6°C (44°F)89 mm (3.5 inches)87%moderate
December Weather3°C (37°F)101 mm (4.0 inches)85%low

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