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December Weather in Iwai, Japan

Last updated: August 23, 2025

In December, the average temperature in Iwai, Japan is a brisk 7°C (44°F), with potential extremes ranging from a chilly -4°C (26°F) to a pleasant 21°C (70°F). Expect 54 mm (2.1 in) of precipitation spread over about 6 days, contributing to an average humidity of 78%. Stay prepared for the varied weather conditions!

December Temperature in Iwai

In December in Iwai, the average temperature is 7°C (44°F). The maximum can reach 21°C (70°F), while the minimum can drop as low as -4°C (26°F). This range makes it advisable for travelers to pack layers to comfortably adapt to the varying temperatures throughout the day.

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

The chart illustrates December temperature patterns in Iwai, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Iwai, December typically has an average temperature of 7°C (44°F), with highs reaching up to 21°C (70°F) and lows dropping to around -4°C (26°F).
JanFebMarAprMayJunJulAugSepOctNovDec394250576772798274655544
Data source: Temperature data for Iwai 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 Iwai

In Iwai in December, the total precipitation amount is 54 mm (2.1 in) over the course of 6 days.

December Precipitation Trends in Iwai

The chart displays monthly precipitation patterns in Iwai, 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 Iwai, December typically receives around 54 mm (2.1 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec42391241091221422251121712387254
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Iwai

In Iwai in December, humidity is 78%. With an average temperature of 7°C (44°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities less enjoyable and prompting travelers to seek cozy indoor spaces or warm beverages for comfort.

December Average Humidity in Iwai

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

In Iwai in December, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Iwai, you can check the information here.

Maximum UV Index Levels in Iwai for December

The chart shows the monthly maximum UV Index (UVI) for Iwai 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 Iwai typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3579101111109753
Data source: Iwai 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 Iwai Compares to Other Months

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

This table compares monthly weather conditions in Iwai, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather4°C (40°F)42 mm (1.6 inches)76%moderate
February Weather6°C (42°F)39 mm (1.5 inches)74%moderate
March Weather10°C (50°F)123 mm (4.9 inches)70%high
April Weather14°C (58°F)109 mm (4.3 inches)74%very high
May Weather19°C (67°F)121 mm (4.8 inches)81%very high
June Weather22°C (72°F)142 mm (5.6 inches)88%extreme
July Weather26°C (79°F)225 mm (8.9 inches)93%extreme
August Weather28°C (82°F)111 mm (4.4 inches)90%very high
September Weather24°C (75°F)171 mm (6.7 inches)86%very high
October Weather18°C (65°F)238 mm (9.4 inches)83%high
November Weather13°C (55°F)72 mm (2.8 inches)80%moderate
December Weather7°C (44°F)54 mm (2.1 inches)78%moderate

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