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September Weather in Johnstown, United States

Last updated: June 24, 2025

In September, the average temperature in Johnstown, United States hovers around 17°C (63°F). Expect a range from a chilly 2°C (35°F) to a warm 32°C (90°F). With 90 mm (3.5 in) of precipitation spread over 9 days, you'll want to be prepared for some rain. Humidity levels are typically around 72%, adding to the overall climate experience.

September Temperature in Johnstown

In September in Johnstown, the average temperature is 17°C (63°F). Maximums can reach 32°C (90°F) and minimums can be as low as 2°C (35°F). This makes it a great time for travelers to experience a comfortable climate while enjoying the various outdoor activities that Johnstown has to offer.

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

The chart illustrates September temperature patterns in Johnstown, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Johnstown, September typically has an average temperature of 17°C (63°F), with highs reaching up to 32°C (90°F) and lows dropping to around 2°C (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec232633455766727063523729
Data source: Temperature data for Johnstown 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 Johnstown

In Johnstown in September, the precipitation amount is 90 mm (3.5 in) over the course of 9 days.

September Precipitation Trends in Johnstown

The chart displays monthly precipitation patterns in Johnstown, 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 Johnstown, September typically receives around 90 mm (3.5 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec85101841291089812110090158105108
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Johnstown

In Johnstown in September, humidity is 72%. With an average temperature of 17°C (63°F), this humidity feels like a muggy embrace, making outdoor activities a bit sticky and requiring plenty of hydration for a comfortable travel experience.

September Average Humidity in Johnstown

This chart illustrates the average monthly humidity levels in Johnstown, 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 Johnstown is approximately 72%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec90%88%86%84%76%72%67%64%72%81%87%85%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Johnstown

In Johnstown 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 Johnstown.

Maximum UV Index Levels in Johnstown for September

The chart shows the monthly maximum UV Index (UVI) for Johnstown 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 Johnstown typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3468910997632
Data source: Johnstown 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 Johnstown Compares to Other Months

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

This table compares monthly weather conditions in Johnstown, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-5°C (24°F)85 mm (3.3 inches)89%moderate
February Weather-3°C (26°F)101 mm (4.0 inches)88%moderate
March Weather0°C (33°F)84 mm (3.3 inches)86%high
April Weather7°C (45°F)129 mm (5.1 inches)84%very high
May Weather14°C (58°F)108 mm (4.2 inches)76%very high
June Weather19°C (66°F)98 mm (3.9 inches)72%very high
July Weather22°C (72°F)121 mm (4.7 inches)66%very high
August Weather21°C (70°F)100 mm (3.9 inches)64%very high
September Weather17°C (63°F)90 mm (3.5 inches)72%high
October Weather11°C (52°F)158 mm (6.2 inches)81%high
November Weather3°C (38°F)105 mm (4.1 inches)87%moderate
December Weather-2°C (29°F)108 mm (4.2 inches)84%low

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