The deaths occurred during the last 48 hours in different parts of the oil and gas rich Balochistan province that borders Iran and Afghanistan.
"Nine persons including four children and a woman died in the torrential rain," Zahid Saleem, chief of the province's disaster management authority, told AFP.
He said four children and a woman were killed today after a roof caved in due to heavy rains in Sheerani district.
"In other incidents, three people were killed in two districts of Mastung and Loralai during the last two days".
Saleem added one person also died after being struck by lightening in Dalbandin district. The local meteorological office said more rain was forecasted across the province over the weekend.
Every year Pakistan is hit by severe weather patterns, which have killed hundreds and wiped out millions of acres of prime farmland in recent years, harming the heavily agrarian economy.
During the rainy season last summer, torrential downpours and flooding killed 81 people and affected almost 300,000 Pakistanis across the country.