The weather forecast for September 10 predicts cloudy conditions with rain and thunderstorms, particularly affecting Western and Central Bulgaria. Eastern Bulgaria is expected to remain dry. A mild southeasterly breeze will be present, intensifying to a mild to moderate strength in Eastern Bulgaria. As the day progresses, a west-northwesterly wind will introduce cooler air to the Danubian Plain. High temperatures will range from 19°C to 24°C in Western Bulgaria and reach up to 31°C in Eastern Bulgaria.

On the coast, overcast skies will dominate, though no precipitation is anticipated. Clouds are expected to partially clear by the afternoon, with a mild to moderate southeasterly wind continuing. High temperatures will be between 25°C and 28°C, while the seawater temperature will range from 25°C to 26°C. Sea waves will be at 2 degrees on the Douglas scale.

In the mountains, conditions will be cloudy with rain and thunderstorms, except in Eastern Bulgaria where it will be dry. A moderate to strong south-southwesterly wind will be observed. High temperatures are forecasted to reach 16°C at 1,200 meters and 10°C at 2,000 meters.