Last updated: June 24, 2025
In December, the average temperature in Walnut, United States hovers around 0°C (33°F), making for a chilly atmosphere. Temperatures can drop as low as -21°C (-6°F) and, on rare occasions, rise to a pleasant 20°C (69°F). Expect about 49 mm (1.9 in) of precipitation spread over 6 days, while humidity lingers at a damp 84%. Stay warm and prepare for a mix of weather!
In December in Walnut, the average temperature is 0°C (33°F). Maximums can reach 20°C (69°F) and minimums can be as low as -21°C (-6°F). It's essential to pack accordingly, as the weather can vary significantly, ranging from chilly to pleasantly warm.
In Walnut in December, the precipitation amount is 49 mm (1.9 in) over the course of 6 days.
In Walnut in December humidity is 84%. With average temperature 0°C (33°F), this humidity feels like a damp chill that seeps into your bones, making outdoor adventures less enjoyable and travel plans challenging.
In Walnut 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 Walnut, you can visit Hourly UV Index in Walnut.
UV Risk Categories
Weather in Walnut varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Walnut, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -4°C (25°F) | 58 mm (2.3 inches) | 82% | moderate |
| February Weather | -3°C (27°F) | 62 mm (2.5 inches) | 83% | moderate |
| March Weather | 4°C (40°F) | 94 mm (3.7 inches) | 84% | high |
| April Weather | 10°C (49°F) | 114 mm (4.5 inches) | 85% | very high |
| May Weather | 17°C (62°F) | 173 mm (6.8 inches) | 79% | very high |
| June Weather | 23°C (73°F) | 146 mm (5.7 inches) | 82% | very high |
| July Weather | 24°C (76°F) | 100 mm (3.9 inches) | 80% | very high |
| August Weather | 23°C (74°F) | 68 mm (2.7 inches) | 81% | very high |
| September Weather | 20°C (69°F) | 110 mm (4.3 inches) | 80% | very high |
| October Weather | 12°C (55°F) | 127 mm (5.0 inches) | 82% | high |
| November Weather | 4°C (39°F) | 55 mm (2.2 inches) | 88% | moderate |
| December Weather | 0°C (33°F) | 49 mm (1.9 inches) | 84% | low |