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December Weather in Iruma, Japan

Last updated: August 23, 2025

In December, the average temperature in Iruma, Japan hovers around 5°C (42°F). Expect a chilly dip to a minimum of -5°C (23°F), while sunny spells can bring highs of 20°C (69°F). With an average humidity of 78% and around 62 mm (2.4 in) of precipitation over 9 days, be prepared for damp days as well as delightful ones!

December Temperature in Iruma

In December in Iruma, the average temperature is 5°C (42°F). Maximums can reach 20°C (69°F), while minimums can drop as low as -5°C (23°F). Be prepared for a wide range of temperatures when traveling during this month.

December Weather in Iruma: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Iruma, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Iruma, December typically has an average temperature of 5°C (42°F), with highs reaching up to 20°C (69°F) and lows dropping to around -5°C (23°F).
JanFebMarAprMayJunJulAugSepOctNovDec373946546368757971615242
Data source: Temperature data for Iruma 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.

December Precipitation in Iruma

In Iruma in December, the precipitation amount is 62 mm (2.4 in) over the course of 9 days.

December Precipitation Trends in Iruma

The chart displays monthly precipitation patterns in Iruma, with values for each month alongside December’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December’s conditions compare to those of other months. In Iruma, December typically receives around 62 mm (2.4 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec53621661501482093121952473467262
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Iruma

In Iruma in December, humidity is 78%. With an average temperature of 5°C (42°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities less enjoyable and urging travelers to bundle up against the cold, sticky air.

December Average Humidity in Iruma

This chart illustrates the average monthly humidity levels in Iruma, with December’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In December, average humidity in Iruma is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%74%70%74%82%88%93%90%86%83%80%78%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Iruma

In Iruma in December, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Iruma for better planning.

Maximum UV Index Levels in Iruma for December

The chart shows the monthly maximum UV Index (UVI) for Iruma in December, 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 December, the maximum UV index in Iruma typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec46891111111110754
Data source: Iruma December 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 December Weather in Iruma Compares to Other Months

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

This table compares monthly weather conditions in Iruma, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather3°C (37°F)53 mm (2.1 inches)76%moderate
February Weather4°C (40°F)62 mm (2.4 inches)74%high
March Weather8°C (47°F)166 mm (6.5 inches)70%very high
April Weather12°C (54°F)150 mm (5.9 inches)74%very high
May Weather17°C (64°F)148 mm (5.8 inches)81%extreme
June Weather20°C (69°F)209 mm (8.2 inches)88%extreme
July Weather24°C (76°F)312 mm (12.3 inches)93%extreme
August Weather26°C (79°F)195 mm (7.7 inches)90%extreme
September Weather22°C (71°F)247 mm (9.7 inches)86%very high
October Weather16°C (61°F)346 mm (13.6 inches)83%high
November Weather11°C (52°F)72 mm (2.8 inches)80%moderate
December Weather5°C (42°F)62 mm (2.4 inches)78%moderate

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