Torrential rains have lashed six provinces in the centre of the country since Saturday, killing thousands of cows and chickens and flooding several cities - including the coastal resort town of Danang.
More than 50 centimetres (20 inches) of rain hit some areas, with more downpours expected in the coming days, the disaster management office said on Thursday.
Vietnam flood and landslide toll hits 54
"Thirteen people were killed, while one remains missing in Quang Ngai province," the office said.
Around 12,000 hectares of crops were destroyed, and some 160,000 livestock killed, it added.
One farmer in Quang Nam province said he lost all his chickens in the flooding, costing him tens of thousands of dollars.
"The water receded but thousands of our chickens were dead. We had to collect them for burial as the smell was so bad," Nguyen Thanh said, quoted by state-run Tuoi Tre newspaper.
Vietnam flood death toll rises to 27, more rain forecast
Several areas in Quang Nam and Quang Ngai provinces were still inundated on Thursday after hydropower plants discharged reservoir waters.
Vietnam is frequently hit by heavy downpours during the typhoon season from May to October, but forecasters said the rains arrived late this year.
More than 200 people have been killed in weather-related disasters in 2018, down from 389 last year.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ