nomadseason

December Weather in Iiyama, Japan

Last updated: August 23, 2025

In Iiyama, Japan, the average temperature in December hovers around 1°C (34°F). During this month, you can expect minimum temperatures to dip as low as -10°C (14°F), while maximum highs can reach up to 19°C (66°F). With 151 mm (6.0 in) of precipitation spread over 20 days, along with an average humidity of 86%, be prepared for a moist and chilly climate!

December Temperature in Iiyama

In December, in Iiyama, the average temperature is 1°C (34°F). The maximum can reach 19°C (66°F), while the minimum can dip as low as -10°C (14°F). Travelers should be prepared for a wide range of temperatures during this time.

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

The chart illustrates December temperature patterns in Iiyama, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Iiyama, December typically has an average temperature of 1°C (34°F), with highs reaching up to 19°C (66°F) and lows dropping to around -10°C (14°F).
JanFebMarAprMayJunJulAugSepOctNovDec293038485965727566564434
Data source: Temperature data for Iiyama generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Iiyama

In Iiyama in December, the total precipitation amount is 151 mm (6.0 in) spread over 20 days.

December Precipitation Trends in Iiyama

The chart displays monthly precipitation patterns in Iiyama, 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 Iiyama, December typically receives around 151 mm (6.0 inches) of precipitation spread over approximately 20 days.
JanFebMarAprMayJunJulAugSepOctNovDec14412913314116017134119819421794151
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

December Humidity in Iiyama

In Iiyama in December, humidity is 86%. With an average temperature of 1°C (34°F), this humidity feels like a chilling embrace, making outdoor adventures brisk and invigorating but challenging for travel.

December Average Humidity in Iiyama

This chart illustrates the average monthly humidity levels in Iiyama, 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 Iiyama is approximately 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%81%79%81%88%92%92%89%87%85%86%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Iiyama

In Iiyama 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 Iiyama, you can check the information here.

Maximum UV Index Levels in Iiyama for December

The chart shows the monthly maximum UV Index (UVI) for Iiyama 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 Iiyama typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec46991111111110753
Data source: Iiyama 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 Iiyama Compares to Other Months

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

This table compares monthly weather conditions in Iiyama, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)144 mm (5.7 inches)88%moderate
February Weather-1°C (30°F)129 mm (5.1 inches)86%high
March Weather4°C (39°F)133 mm (5.2 inches)81%very high
April Weather9°C (48°F)141 mm (5.5 inches)78%very high
May Weather15°C (59°F)160 mm (6.3 inches)81%extreme
June Weather18°C (65°F)171 mm (6.7 inches)88%extreme
July Weather22°C (73°F)341 mm (13.4 inches)92%extreme
August Weather24°C (75°F)198 mm (7.8 inches)92%extreme
September Weather19°C (67°F)194 mm (7.6 inches)89%very high
October Weather13°C (56°F)217 mm (8.5 inches)87%high
November Weather7°C (44°F)94 mm (3.7 inches)85%moderate
December Weather1°C (34°F)151 mm (6.0 inches)86%moderate

Compare Iiyama's Climate with Cities Worldwide