Recent heavy rains and flooding have killed 51 people in Niger, Reuters news agency quotes officials as saying.
More than 26,000 houses have collapsed and some 280,000 people are in need of help, President Mahamadou Issoufou said.
In Sudan, 89 people have died as a result of rains and flooding, AFP news agency reports, quoting officials.
More than 38,000 homes have been destroyed.
"The Blue Nile has reached an all-time high since records began more than a century ago," AFP quotes a statement from the irrigation and water ministry as saying.