Last updated: June 24, 2025
In Rockville, United States, the average temperature in December hovers around 2°C (36°F), but you can expect some variation—temperatures can dip as low as -19°C (-2°F) or rise up to 18°C (64°F). Rainfall is common during this time, with approximately 75 mm (3.0 in) of precipitation spread over 10 days. Additionally, the average humidity levels are quite high at 87%, contributing to the overall chilliness of the month.
In December in Rockville, the average temperature is 2°C (36°F), with maximums reaching 18°C (64°F) and minimums dropping as low as -19°C (-2°F). Travelers should be prepared for a wide range of temperatures during their visit.
In Rockville in December, the precipitation amount is 75 mm (3.0 in) spread over a duration of 10 days.
In Rockville in December, humidity is 87%. With an average temperature of 2°C (36°F), this humidity feels like an unwelcome chill that seeps into your bones, making outdoor exploration feel damp and heavy, and encouraging travelers to seek the warmth of indoor attractions instead.
In Rockville 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 Rockville, you can check the information here.
UV Risk Categories
Weather in Rockville varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Rockville, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -1°C (30°F) | 84 mm (3.3 inches) | 87% | moderate |
| February Weather | 1°C (33°F) | 88 mm (3.5 inches) | 85% | moderate |
| March Weather | 6°C (43°F) | 122 mm (4.8 inches) | 86% | high |
| April Weather | 11°C (53°F) | 106 mm (4.2 inches) | 84% | very high |
| May Weather | 18°C (65°F) | 140 mm (5.5 inches) | 79% | very high |
| June Weather | 24°C (75°F) | 113 mm (4.5 inches) | 82% | extreme |
| July Weather | 25°C (78°F) | 103 mm (4.1 inches) | 79% | very high |
| August Weather | 24°C (75°F) | 100 mm (3.9 inches) | 70% | very high |
| September Weather | 21°C (71°F) | 64 mm (2.5 inches) | 69% | very high |
| October Weather | 14°C (58°F) | 118 mm (4.6 inches) | 76% | high |
| November Weather | 5°C (42°F) | 87 mm (3.4 inches) | 88% | moderate |
| December Weather | 2°C (36°F) | 75 mm (3.0 inches) | 87% | moderate |