Officials estimate as many as 13 million people have been afflicted, while the United Nations has put the number at roughly 4 million.
Downpours Saturday swelled rivers and streams and Pakistani meteorologist Farooq Dar said heavy rain in Afghanistan is expected to affect Pakistan on Sunday.
About 30,000 soldiers are rebuilding bridges, delivering food and setting up relief camps in the northwest.
Millions of dollars of aid has been donated from abroad.
NATO said in a statement Saturday that Pakistan had asked for help dealing with the flood. The alliance said it would help coordinate assistance, including aid transport.