Bulgaria's weather service has issued a yellow warning for heavy rain today in Dobrich region and parts of Silistra region.
Rain is expected in many places in the eastern half of the country. In the northeast, it will be heavy in places, with thunder.
Under a yellow warning, the National Institute of Meteorology and Hydrology (NIMH) says there may be local floods, though only a few. It says outdoor work may have to stop.
Poor visibility and aquaplaning could make driving harder.
Later today the rain will spread across most of northern Bulgaria. In the southeast it will stop.