The cost of federal flood insurance will rise.

Premiums will increase by an average of 27% on Oct. 1, the Federal Insurance Administration announced. The rate hike is intended to put the program into the black, based on losses in an average year. The increase will boost average annual charges for $60,000 worth of insurance to $255 from $201. In the highest-risk areas, however--coastal zones where the danger of floods is compounded by waves--the average annual premium for $60,000 insurance will rise to about $540. The program was set up in 1968 to provide coverage not available from private insurance agencies.