Last updated: August 22, 2025
In Sliven, Bulgaria, the average temperature in December typically hovers around 3°C (38°F). During this time, temperatures can dip as low as -9°C (16°F) and soar to a high of 16°C (61°F). Expect about 89 mm (3.5 in) of precipitation spread over 13 days, contributing to an average humidity level of 87%. Prepare for a chilly, damp month!
In December in Sliven, the average temperature is 3°C (38°F). The maximum can reach 16°C (61°F), while the minimum can drop as low as -9°C (16°F). Be prepared for chilly weather and pack accordingly if you plan to visit during this time.
In Sliven in December, the precipitation amount is 89 mm (3.5 in) distributed over 13 days.
In Sliven in December humidity is 87%. With an average temperature of 3°C (38°F), this humidity feels like a chilly blanket wrapped around you, making travel quite uncomfortable as the cold dampness seeps into your clothes and lingers in the air, often leaving you shivering and longing for warmer, drier conditions.
In Sliven 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 Sliven, you can visit Hourly UV Index in Sliven.
UV Risk Categories
Weather in Sliven varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Sliven, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 0°C (33°F) | 54 mm (2.1 inches) | 88% | low |
| February Weather | 3°C (38°F) | 55 mm (2.2 inches) | 84% | moderate |
| March Weather | 5°C (42°F) | 75 mm (2.9 inches) | 81% | high |
| April Weather | 10°C (50°F) | 58 mm (2.3 inches) | 70% | very high |
| May Weather | 15°C (60°F) | 91 mm (3.6 inches) | 72% | very high |
| June Weather | 19°C (67°F) | 150 mm (5.9 inches) | 66% | very high |
| July Weather | 22°C (72°F) | 82 mm (3.2 inches) | 62% | very high |
| August Weather | 23°C (73°F) | 36 mm (1.4 inches) | 48% | very high |
| September Weather | 18°C (65°F) | 29 mm (1.2 inches) | 58% | high |
| October Weather | 13°C (55°F) | 70 mm (2.7 inches) | 78% | high |
| November Weather | 8°C (46°F) | 59 mm (2.3 inches) | 85% | moderate |
| December Weather | 3°C (38°F) | 89 mm (3.5 inches) | 87% | low |