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September Weather in Castleisland, Ireland

Last updated: August 23, 2025

In September, the average temperature in Castleisland, Ireland hovers around 13°C (56°F). Expect a minimum of 2°C (36°F) and a comfortable maximum of 26°C (79°F). The region experiences 80 mm (3.2 in) of precipitation, spread over approximately 16 days, leading to a notably high average humidity of 88%. Prepare for a mix of cool days and occasional rain!

September Temperature in Castleisland

In September in Castleisland, the average temperature is 13°C (56°F). Maximums can reach 26°C (79°F) and minimums can be as low as 2°C (36°F). This makes it a perfect time for travelers to enjoy a range of outdoor activities while dressing in layers to accommodate the varying temperatures.

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

The chart illustrates September temperature patterns in Castleisland, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Castleisland, September typically has an average temperature of 13°C (56°F), with highs reaching up to 26°C (79°F) and lows dropping to around 2°C (36°F).
JanFebMarAprMayJunJulAugSepOctNovDec434444485256595956514645
Data source: Temperature data for Castleisland 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 Castleisland

In Castleisland in September, the total precipitation amount is 80 mm (3.2 in) distributed over 16 days, indicating a relatively wet period.

September Precipitation Trends in Castleisland

The chart displays monthly precipitation patterns in Castleisland, 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 Castleisland, September typically receives around 80 mm (3.2 inches) of precipitation spread over approximately 16 days.
JanFebMarAprMayJunJulAugSepOctNovDec74118104656964681148010996126
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Castleisland

In Castleisland in September, humidity is 88%. With an average temperature of 13°C (56°F), this humidity feels like a thick, warm blanket wrapping around you, making outdoor adventures sticky and challenging.

September Average Humidity in Castleisland

This chart illustrates the average monthly humidity levels in Castleisland, 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 Castleisland is approximately 88%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%88%87%86%83%83%85%85%88%91%92%89%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Castleisland

In Castleisland 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 Castleisland.

Maximum UV Index Levels in Castleisland for September

The chart shows the monthly maximum UV Index (UVI) for Castleisland 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 Castleisland typically reaches 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec124678875421
Data source: Castleisland 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 Castleisland Compares to Other Months

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

This table compares monthly weather conditions in Castleisland, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather6°C (43°F)74 mm (2.9 inches)88%low
February Weather7°C (44°F)118 mm (4.6 inches)88%low
March Weather7°C (44°F)104 mm (4.1 inches)87%moderate
April Weather9°C (48°F)65 mm (2.6 inches)86%high
May Weather11°C (52°F)69 mm (2.7 inches)83%high
June Weather13°C (57°F)64 mm (2.5 inches)83%very high
July Weather15°C (60°F)68 mm (2.7 inches)85%very high
August Weather15°C (59°F)114 mm (4.5 inches)85%high
September Weather13°C (56°F)80 mm (3.2 inches)88%moderate
October Weather10°C (51°F)109 mm (4.3 inches)91%moderate
November Weather8°C (47°F)96 mm (3.8 inches)92%low
December Weather7°C (45°F)126 mm (5.0 inches)89%low

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