Last updated: June 24, 2025
In December, the average temperature in Stony Brook, United States hovers around 4°C (39°F), with a minimum plunging to -11°C (13°F) and a maximum peaking at 17°C (63°F). Expect about 119 mm (4.7 in) of precipitation over 11 days, and prepare for an average humidity level of 80%, making this month both chilly and damp.
In December in Stony Brook, the average temperature is 4°C (39°F). Maximums can reach 17°C (63°F), while minimums can drop as low as -11°C (13°F). Travelers should be prepared for a wide range of temperatures and pack accordingly for both milder and colder conditions.
In Stony Brook in December, the total precipitation amount is 119 mm (4.7 in), which occurs over the course of 11 days.
In Stony Brook in December, humidity is 80%. With an average temperature of 4°C (39°F), this humidity feels like a damp chill that seeps into your bones, making travel uncomfortable and requiring extra layers to stay warm while navigating through the misty streets.
In Stony Brook 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 Stony Brook, you can visit Hourly UV Index in Stony Brook.
UV Risk Categories
Weather in Stony Brook varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Stony Brook, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 1°C (34°F) | 70 mm (2.8 inches) | 84% | moderate |
| February Weather | 2°C (36°F) | 99 mm (3.9 inches) | 82% | moderate |
| March Weather | 5°C (41°F) | 95 mm (3.8 inches) | 81% | high |
| April Weather | 10°C (50°F) | 118 mm (4.7 inches) | 78% | very high |
| May Weather | 15°C (60°F) | 110 mm (4.3 inches) | 69% | very high |
| June Weather | 21°C (70°F) | 90 mm (3.5 inches) | 69% | very high |
| July Weather | 25°C (77°F) | 132 mm (5.2 inches) | 62% | very high |
| August Weather | 24°C (75°F) | 108 mm (4.3 inches) | 65% | very high |
| September Weather | 21°C (69°F) | 92 mm (3.6 inches) | 68% | very high |
| October Weather | 15°C (60°F) | 129 mm (5.1 inches) | 74% | high |
| November Weather | 8°C (47°F) | 94 mm (3.7 inches) | 82% | moderate |
| December Weather | 4°C (39°F) | 119 mm (4.7 inches) | 80% | low |