Last updated: June 24, 2025
In Lake Forest, United States, the average temperature in December hovers around 1°C (35°F), with a chilly minimum of -15°C (5°F) and a comfortable maximum of 15°C (59°F). Expect 75 mm (2.9 in) of precipitation spread over 9 days, coupled with an average humidity of 81%. Whether you're bundling up or dodging raindrops, be prepared for a dynamic climate!
In December in Lake Forest, the average temperature is 1°C (35°F). The maximum can reach 15°C (59°F), and the minimum can be as low as -15°C (5°F). If you're traveling during this time, be prepared for a wide range of temperatures and pack accordingly to stay comfortable.
In Lake Forest, in December, the precipitation amount is 75 mm (2.9 in) spread over the course of 9 days.
In Lake Forest in December, humidity is 81%. With an average temperature of 1°C (35°F), this humidity feels like a thick, cold blanket wrapping around you, making travel uncomfortable and the air heavy, which can dampen your spirits as you navigate through the chilly conditions.
In Lake Forest 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 Lake Forest, you can visit Hourly UV Index in Lake Forest.
UV Risk Categories
Weather in Lake Forest varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Lake Forest, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -2°C (28°F) | 85 mm (3.3 inches) | 85% | low |
| February Weather | -2°C (29°F) | 85 mm (3.3 inches) | 85% | moderate |
| March Weather | 2°C (36°F) | 90 mm (3.6 inches) | 85% | high |
| April Weather | 5°C (41°F) | 125 mm (4.9 inches) | 85% | very high |
| May Weather | 10°C (50°F) | 171 mm (6.7 inches) | 78% | very high |
| June Weather | 16°C (62°F) | 105 mm (4.1 inches) | 80% | very high |
| July Weather | 21°C (71°F) | 69 mm (2.7 inches) | 78% | very high |
| August Weather | 22°C (72°F) | 70 mm (2.8 inches) | 76% | very high |
| September Weather | 19°C (67°F) | 85 mm (3.4 inches) | 79% | very high |
| October Weather | 13°C (55°F) | 161 mm (6.3 inches) | 83% | moderate |
| November Weather | 5°C (41°F) | 77 mm (3.0 inches) | 88% | moderate |
| December Weather | 1°C (35°F) | 75 mm (2.9 inches) | 81% | low |