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September Weather in Johnstown, Ireland

Last updated: August 23, 2025

In September, the average temperature in Johnstown, Ireland hovers around 13°C (56°F), with a range from a brisk 2°C (35°F) to a pleasantly warm 24°C (76°F). Expect some drizzle, as precipitation totals 68 mm (2.7 in) over about 13 days, contributing to an average humidity of 86%. Embrace the cozy vibes of this month!

September Temperature in Johnstown

In September in Johnstown, the average temperature is 13°C (56°F). The maximum can reach 24°C (76°F), while the minimum can drop to as low as 2°C (35°F). It’s advisable to pack layers to stay comfortable while exploring, as the weather can vary significantly throughout the day.

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 13°C (56°F), with highs reaching up to 24°C (76°F) and lows dropping to around 2°C (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec414344475257615956514543
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 68 mm (2.7 in) spread over 13 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 68 mm (2.7 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec557981517273789468828890
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 86%. With an average temperature of 13°C (56°F), this humidity feels like a damp blanket enveloping you, making outdoor activities slightly uncomfortable and prompting travelers to seek shade or air-conditioned spaces frequently.

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 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%86%86%85%83%85%86%85%86%87%87%84%
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 reaches 5, which corresponds to a moderate Exposure Category. Under these conditions, the estimated time to burn is approximately 30 minutes. For more details, 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 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec124578875321
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 Weather5°C (42°F)55 mm (2.2 inches)85%low
February Weather6°C (43°F)79 mm (3.1 inches)86%low
March Weather7°C (44°F)81 mm (3.2 inches)86%moderate
April Weather8°C (47°F)51 mm (2.0 inches)85%moderate
May Weather11°C (53°F)72 mm (2.8 inches)83%high
June Weather14°C (58°F)73 mm (2.9 inches)85%very high
July Weather16°C (61°F)77 mm (3.0 inches)86%very high
August Weather15°C (60°F)94 mm (3.7 inches)85%high
September Weather13°C (56°F)68 mm (2.7 inches)86%moderate
October Weather10°C (51°F)82 mm (3.2 inches)87%moderate
November Weather7°C (46°F)88 mm (3.5 inches)86%low
December Weather6°C (43°F)90 mm (3.5 inches)84%low

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