Last updated: June 24, 2025
In December, the average temperature in Greenwich, United States hovers around 1°C (35°F), with a minimum dipping to -20°C (-3°F) and a maximum reaching 18°C (64°F). Expect around 84 mm (3.3 in) of precipitation over 12 days, and with an average humidity of 86%, it’s safe to say that Greenwich can feel quite brisk and damp.
In December in Greenwich, the average temperature is 1°C (35°F). The maximum can reach 18°C (64°F), while the minimum can be as low as -20°C (-3°F). Travelers should be prepared for a wide range of temperatures, so layering clothing is essential for staying comfortable.
In Greenwich in December, the precipitation amount is 84 mm (3.3 in) over a span of 12 days.
In Greenwich in December, humidity is 86%. With an average temperature of 1°C (35°F), this humidity feels like a biting chill that wraps around you, making outdoor exploration uncomfortable and requiring extra layers to stay warm while navigating the damp air.
In Greenwich 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 Greenwich, you can visit Hourly UV Index in Greenwich.
UV Risk Categories
Weather in Greenwich varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Greenwich, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -2°C (29°F) | 78 mm (3.1 inches) | 88% | moderate |
| February Weather | 0°C (32°F) | 92 mm (3.6 inches) | 87% | moderate |
| March Weather | 4°C (40°F) | 97 mm (3.8 inches) | 87% | high |
| April Weather | 10°C (50°F) | 123 mm (4.8 inches) | 87% | very high |
| May Weather | 16°C (62°F) | 129 mm (5.1 inches) | 81% | very high |
| June Weather | 21°C (71°F) | 136 mm (5.4 inches) | 82% | very high |
| July Weather | 24°C (75°F) | 128 mm (5.0 inches) | 81% | very high |
| August Weather | 22°C (72°F) | 91 mm (3.6 inches) | 78% | very high |
| September Weather | 20°C (67°F) | 79 mm (3.1 inches) | 78% | very high |
| October Weather | 14°C (57°F) | 96 mm (3.8 inches) | 82% | high |
| November Weather | 5°C (41°F) | 88 mm (3.4 inches) | 89% | moderate |
| December Weather | 1°C (35°F) | 84 mm (3.3 inches) | 86% | low |