The climate in Sliven during September can be summarized as mild and reasonably dry.
September is in the fall / autumn in Sliven and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 21°C (70°F), whilst at night 9°C (48°F) is normal.
| Daytime temperature | 21.3°C 70.3°F |
|---|---|
| Nightly temperature | 9.1°C 48.4°F |
| Average temperature | 15.2°C 59.4°F |
| Daily sunshine | 8.5 hrs |
| Avg rainfall | 42 mm 1.6 ins |
| Rainy days | 5 days |
| Sea temperature | 22.6°C 72.6°F |
| Humidity | 67% |
| Windspeed | 9kph 6 mph |
On average September is the driest month of the year in Sliven with around 42mm 1.6 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 5 days, although this may vary considerably.
On the flip side this corresponds to an average of 8.5 hours of sunshine per day.
The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Sliven in September 2025.
Best places to visit in September
| Hottest month: | July | 25°C 77°F |
|---|---|---|
| Driest month: | September | 42mm 1.7ins |
| Sunniest month: | August | 10.1hrs |
| Coldest month: | January | 0.9°C 33.6°F |
| Wettest month: | June | 80mm 3.1ins |