January Weather in Castleknock, Ireland

Last updated: August 23, 2025

In Castleknock, Ireland, the average temperature in January hovers around 5°C (42°F), with minimums dipping to a chilly -3°C (26°F) and maximums reaching a comfortable 13°C (56°F). Expect about 57 mm (2.2 in) of precipitation over 10 days, contributing to an average humidity level of 85%. Stay prepared for a month that is both cool and wet!

January Temperature in Castleknock

In January in Castleknock, the average temperature is 5°C (42°F). The maximum can reach 13°C (56°F), and the minimum can be as low as -3°C (26°F). Travelers should prepare for chilly weather and pack warm clothing to stay comfortable.

January Weather in Castleknock: Daily Temperature Highs, Lows, and Averages

The chart illustrates January temperature patterns in Castleknock, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Castleknock, January typically has an average temperature of 5°C (42°F), with highs reaching up to 13°C (56°F) and lows dropping to around -3°C (26°F).

Data source: Temperature data for Castleknock generated using information from the Copernicus Climate Change Service.

January Precipitation in Castleknock

In Castleknock in January, the precipitation amount is 57 mm (2.2 in) over a span of 10 days.

January Precipitation Trends in Castleknock

The chart displays monthly precipitation patterns in Castleknock, with values for each month alongside January’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how January’s conditions compare to those of other months. In Castleknock, January typically receives around 57 mm (2.2 inches) of precipitation spread over approximately 10 days.

Data source: Precipitation data for January generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

January Humidity in Castleknock

In Castleknock in January, humidity is 85%. With an average temperature of 5°C (42°F), this humidity feels like a damp chill that clings to your skin, making outdoor activities uncomfortable and requiring extra layers to stay warm while exploring.

January Average Humidity in Castleknock

This chart illustrates the average monthly humidity levels in Castleknock, with January’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In January, average humidity in Castleknock is approximately 85%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for January generated using information from the Copernicus Climate Change Service.

January UV Index in Castleknock

In Castleknock in January, the maximum UV index is 1, which corresponds to a low Exposure Category. This means you have a time to burn of 45 minutes. For more details, you can check the Hourly UV Index in Castleknock.

Maximum UV Index Levels in Castleknock for January

The chart shows the monthly maximum UV Index (UVI) for Castleknock in January, 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 January, the maximum UV index in Castleknock typically reaches 1, which falls under the low exposure category.

Data source: Castleknock January 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 January Weather in Castleknock Compares to Other Months

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

This table compares monthly weather conditions in Castleknock, showing how January’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	5°C (42°F)	57 mm (2.2 inches)	85%	low
February Weather	6°C (43°F)	80 mm (3.1 inches)	86%	low
March Weather	7°C (44°F)	81 mm (3.2 inches)	86%	moderate
April Weather	8°C (47°F)	52 mm (2.0 inches)	85%	moderate
May Weather	11°C (52°F)	72 mm (2.8 inches)	83%	high
June Weather	14°C (57°F)	75 mm (3.0 inches)	85%	very high
July Weather	16°C (60°F)	80 mm (3.2 inches)	86%	very high
August Weather	15°C (60°F)	95 mm (3.8 inches)	85%	high
September Weather	13°C (56°F)	73 mm (2.9 inches)	86%	moderate
October Weather	11°C (51°F)	87 mm (3.4 inches)	87%	moderate
November Weather	8°C (46°F)	97 mm (3.8 inches)	86%	low
December Weather	6°C (44°F)	94 mm (3.7 inches)	84%	low