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September Weather in Portlaoise, Ireland

Last updated: August 23, 2025

In September, the average temperature in Portlaoise, Ireland hovers around 13°C (56°F). Expect a minimum of 0°C (32°F) and a maximum of 26°C (79°F), making it a month of varied weather. With precipitation totaling 66 mm (2.6 in) over 12 days, it’s wise to keep an umbrella handy. Additionally, the average humidity sits at a high 86%, adding a touch of dampness to the air.

September Temperature in Portlaoise

In September in Portlaoise, the average temperature is 13°C (56°F). Maximum temperatures can reach 26°C (79°F), while minimum temperatures can drop as low as 0°C (32°F). It's advisable to pack layers to stay comfortable during your travels.

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

The chart illustrates September temperature patterns in Portlaoise, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Portlaoise, 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 0°C (32°F).
JanFebMarAprMayJunJulAugSepOctNovDec424344475358615956514643
Data source: Temperature data for Portlaoise 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 Portlaoise

In Portlaoise in September, the precipitation amount is 66 mm (2.6 in) over the course of 12 days.

September Precipitation Trends in Portlaoise

The chart displays monthly precipitation patterns in Portlaoise, 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 Portlaoise, September typically receives around 66 mm (2.6 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec568881506668699466888498
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Portlaoise

In Portlaoise 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 Portlaoise

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

In Portlaoise 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 Portlaoise.

Maximum UV Index Levels in Portlaoise for September

The chart shows the monthly maximum UV Index (UVI) for Portlaoise 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 Portlaoise typically reaches 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec124578875321
Data source: Portlaoise 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 Portlaoise Compares to Other Months

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

This table compares monthly weather conditions in Portlaoise, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather6°C (42°F)56 mm (2.2 inches)85%low
February Weather6°C (43°F)88 mm (3.4 inches)86%low
March Weather7°C (44°F)81 mm (3.2 inches)86%moderate
April Weather9°C (48°F)50 mm (2.0 inches)85%moderate
May Weather11°C (53°F)66 mm (2.6 inches)83%high
June Weather14°C (58°F)68 mm (2.7 inches)85%very high
July Weather16°C (61°F)69 mm (2.7 inches)86%very high
August Weather15°C (60°F)94 mm (3.7 inches)85%high
September Weather13°C (56°F)66 mm (2.6 inches)86%moderate
October Weather10°C (51°F)87 mm (3.4 inches)87%moderate
November Weather8°C (46°F)84 mm (3.3 inches)86%low
December Weather6°C (44°F)98 mm (3.8 inches)84%low

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