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September Weather in Castletown, Ireland

Last updated: August 23, 2025

In September, the average temperature in Castletown, Ireland hovers around 14°C (57°F). Expect a cool minimum of 3°C (37°F) and a warm maximum of 23°C (73°F). With 76 mm (3.0 in) of precipitation spread over 13 days, it’s wise to carry an umbrella. The air is quite humid, averaging around 86%, making it a perfect time to enjoy the local scenery!

September Temperature in Castletown

In September in Castletown, the average temperature is 14°C (57°F). Maximums can reach 23°C (73°F) and minimums can drop as low as 3°C (37°F). This mild weather makes Castletown a pleasant destination for travelers seeking comfortable conditions for outdoor activities and exploration.

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

The chart illustrates September temperature patterns in Castletown, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Castletown, September typically has an average temperature of 14°C (57°F), with highs reaching up to 23°C (73°F) and lows dropping to around 3°C (37°F).
JanFebMarAprMayJunJulAugSepOctNovDec434344475257616057524744
Data source: Temperature data for Castletown 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 Castletown

In Castletown in September, the total precipitation amount is 76 mm (3.0 in), which occurs over the course of 13 days.

September Precipitation Trends in Castletown

The chart displays monthly precipitation patterns in Castletown, 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 Castletown, September typically receives around 76 mm (3.0 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec53887955706768967693108107
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Castletown

In Castletown in September humidity is 86%. With an average temperature of 14°C (57°F), this humidity feels like a heavy blanket enveloping you, making travel feel oppressive and uncomfortably sticky.

September Average Humidity in Castletown

This chart illustrates the average monthly humidity levels in Castletown, 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 Castletown 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 Castletown

In Castletown 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 Castletown.

Maximum UV Index Levels in Castletown for September

The chart shows the monthly maximum UV Index (UVI) for Castletown 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 Castletown typically reaches 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec124578875421
Data source: Castletown 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 Castletown Compares to Other Months

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

This table compares monthly weather conditions in Castletown, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather6°C (43°F)53 mm (2.1 inches)85%low
February Weather6°C (44°F)87 mm (3.4 inches)86%low
March Weather7°C (45°F)79 mm (3.1 inches)86%moderate
April Weather8°C (47°F)55 mm (2.2 inches)85%moderate
May Weather11°C (52°F)70 mm (2.8 inches)83%high
June Weather14°C (57°F)67 mm (2.6 inches)85%very high
July Weather16°C (61°F)68 mm (2.7 inches)86%very high
August Weather15°C (60°F)96 mm (3.8 inches)85%high
September Weather14°C (57°F)76 mm (3.0 inches)86%moderate
October Weather11°C (52°F)93 mm (3.6 inches)87%moderate
November Weather8°C (47°F)108 mm (4.3 inches)86%low
December Weather7°C (44°F)107 mm (4.2 inches)84%low

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