December Weather in Yanai, Japan

Last updated: August 23, 2025

In December, the average temperature in Yanai, Japan hovers around 9°C (49°F), with comfortable highs reaching up to 20°C (68°F) and cooler lows dipping to 1°C (34°F). Expect about 64 mm (2.5 in) of precipitation spread over 8 days, contributing to an average humidity of 79%, making for a damp but refreshing atmosphere.

December Temperature in Yanai

In December in Yanai, the average temperature is 9°C (49°F). Maximums can reach 20°C (68°F) and minimums can be as low as 1°C (34°F). This makes it a great time for travelers to enjoy the cool weather while exploring the beautiful sights of Yanai.

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

The chart illustrates December temperature patterns in Yanai, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Yanai, December typically has an average temperature of 9°C (49°F), with highs reaching up to 20°C (68°F) and lows dropping to around 1°C (34°F).

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

December Precipitation in Yanai

In Yanai in December, the precipitation amount is 64 mm (2.5 in) over the course of 8 days.

December Precipitation Trends in Yanai

The chart displays monthly precipitation patterns in Yanai, 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 Yanai, December typically receives around 64 mm (2.5 inches) of precipitation spread over approximately 8 days.

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

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Millimeters (mm) Inches (in)

December Humidity in Yanai

In Yanai in December humidity is 79%. With an average temperature of 9°C (49°F), this humidity feels like a damp chill that seeps into your bones, making it essential to dress in layers and carrying a light raincoat for a comfortable travel experience.

December Average Humidity in Yanai

This chart illustrates the average monthly humidity levels in Yanai, 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 Yanai is approximately 79%, offering insight into how humid the weather typically is during this month.

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

December UV Index in Yanai

In Yanai 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 Yanai for better planning.

Maximum UV Index Levels in Yanai for December

The chart shows the monthly maximum UV Index (UVI) for Yanai 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 Yanai typically reaches 4, which falls under the moderate exposure category.

Data source: Yanai 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 Yanai Compares to Other Months

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

This table compares monthly weather conditions in Yanai, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	7°C (45°F)	54 mm (2.1 inches)	75%	moderate
February Weather	7°C (45°F)	79 mm (3.1 inches)	71%	moderate
March Weather	11°C (51°F)	127 mm (5.0 inches)	71%	very high
April Weather	14°C (58°F)	146 mm (5.7 inches)	78%	extreme
May Weather	18°C (65°F)	159 mm (6.3 inches)	84%	extreme
June Weather	22°C (72°F)	189 mm (7.5 inches)	86%	extreme
July Weather	26°C (79°F)	355 mm (14.0 inches)	92%	extreme
August Weather	28°C (82°F)	221 mm (8.7 inches)	91%	extreme
September Weather	24°C (76°F)	215 mm (8.5 inches)	84%	very high
October Weather	20°C (68°F)	173 mm (6.8 inches)	83%	high
November Weather	15°C (59°F)	43 mm (1.7 inches)	81%	high
December Weather	9°C (49°F)	64 mm (2.5 inches)	79%	moderate