Tsarevo has switched on the BG-ALERT early warning system ahead of rain forecast for the night of October 2. The mayor signed the notice.
Officials are urging people in town and visitors to stay away from spots where water could pool.
"We're asking residents and visitors to avoid low-lying areas and stay away from rivers, ravines and other waterways," the mayor said in the notice. Anyone who needs help should call 112.
Tomorrow's forecast for the Black Sea coast calls for mostly sunny weather, with clouds building up in the afternoon. The buildup will be stronger along the southern coast, where rain is expected.