Last updated: June 24, 2025
In Sumter, United States, the average temperature in December hovers around 10°C (51°F). Be prepared for a range of temperatures, as it can dip to a chilly -6°C (21°F) or rise to a warm 26°C (80°F). With an average humidity of 87%, the air can feel quite damp. Expect 141 mm (5.5 in) of precipitation over about 10 days during this month, so it’s wise to bring your umbrella!
In December in Sumter, the average temperature is 10°C (51°F). Maximums can reach 26°C (80°F), while minimums can drop as low as -6°C (21°F). This variability means travelers should be prepared for both mild and chilly conditions, making layers essential for any outdoor activities.
In Sumter in December, the precipitation amount is 141 mm (5.5 in) over a span of 10 days.
In Sumter in December humidity is 87%. With an average temperature of 10°C (51°F), this humidity feels like a heavy blanket enveloping you, making outdoor activities uncomfortable and sticky, and often requiring frequent breaks to stay hydrated and cool.
In Sumter in December, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Sumter for better planning.
UV Risk Categories
Weather in Sumter varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Sumter, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 9°C (48°F) | 78 mm (3.1 inches) | 86% | moderate |
| February Weather | 12°C (54°F) | 95 mm (3.7 inches) | 81% | high |
| March Weather | 14°C (58°F) | 70 mm (2.8 inches) | 81% | very high |
| April Weather | 18°C (65°F) | 102 mm (4.0 inches) | 79% | very high |
| May Weather | 23°C (74°F) | 97 mm (3.8 inches) | 75% | extreme |
| June Weather | 26°C (79°F) | 122 mm (4.8 inches) | 75% | extreme |
| July Weather | 28°C (82°F) | 144 mm (5.7 inches) | 80% | extreme |
| August Weather | 27°C (81°F) | 128 mm (5.0 inches) | 81% | very high |
| September Weather | 25°C (78°F) | 136 mm (5.4 inches) | 83% | very high |
| October Weather | 21°C (69°F) | 56 mm (2.2 inches) | 78% | very high |
| November Weather | 13°C (55°F) | 67 mm (2.6 inches) | 85% | high |
| December Weather | 10°C (51°F) | 141 mm (5.5 inches) | 87% | moderate |