Last updated: August 23, 2025
In December, the average temperature in Iwanai, Japan hovers around -2°C (29°F). Expect brisk conditions with minimums plummeting to -12°C (11°F) and maximums reaching up to 11°C (52°F). The month typically features 159 mm (6.3 in) of precipitation spread over 27 days, contributing to an overall average humidity of 80%. Bundle up and prepare for a wet, chilly experience!
In December in Iwanai, average temperature is -2°C (29°F). Maximum can reach 11°C (52°F) and minimum can be as low as -12°C (11°F). Travelers should be prepared for chilly weather and dress in layers to stay warm while exploring.
In Iwanai in December, the total precipitation amount is 159 mm (6.3 in) spread over 27 days.
In Iwanai in December humidity is 80%. With an average temperature of -2°C (29°F), this humidity feels like a heavy, biting chill that seeps into your bones, making outdoor exploration uncomfortable and requiring extra layers to ward off both the cold and the dampness.
In Iwanai in December, the maximum UV index is 2, which corresponds to a low exposure category. With this level of UV radiation, the time to burn is approximately 45 minutes. To learn more about the hourly UV index in Iwanai, you can visit Hourly UV Index in Iwanai.
UV Risk Categories
Weather in Iwanai varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Iwanai, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -4°C (25°F) | 99 mm (3.9 inches) | 84% | low |
| February Weather | -3°C (26°F) | 103 mm (4.1 inches) | 83% | moderate |
| March Weather | 1°C (34°F) | 98 mm (3.8 inches) | 81% | moderate |
| April Weather | 5°C (41°F) | 88 mm (3.4 inches) | 81% | high |
| May Weather | 11°C (53°F) | 86 mm (3.4 inches) | 86% | very high |
| June Weather | 15°C (59°F) | 109 mm (4.3 inches) | 87% | very high |
| July Weather | 20°C (68°F) | 94 mm (3.7 inches) | 93% | very high |
| August Weather | 21°C (70°F) | 145 mm (5.7 inches) | 95% | very high |
| September Weather | 18°C (64°F) | 126 mm (5.0 inches) | 88% | very high |
| October Weather | 12°C (53°F) | 149 mm (5.9 inches) | 83% | moderate |
| November Weather | 5°C (41°F) | 176 mm (6.9 inches) | 79% | moderate |
| December Weather | -2°C (29°F) | 159 mm (6.3 inches) | 80% | low |