In worst-hit Vietnam, the fatalities rose to 233, with nine confirmed dead in northern Thailand -- where one district is suffering its worst floods in 80 years.
Myanmar's national fire service confirmed the country's first Yagi-related deaths after 17 bodies were recovered from flooded villages in the Mandalay region, while more than 50,000 people have been forced from their homes.
Yagi brought a colossal deluge of rain that has inundated a swathe of northern Vietnam, Laos, Thailand and Myanmar, triggering deadly landslides and widespread river flooding.
One farmer on the edge of Hanoi told AFP his entire 1,800 square metre peach blossom plantation was submerged, destroying all 400 of his trees.
"It will be so hard for me to recover from this loss -- I think I will lose up to $40,000 this season," said the farmer, who gave his name only as Tu.
"I really don't know what to do now, I'm just waiting for the water to recede."
The United Nations children's agency (UNICEF) said the typhoon had damaged more than 140,000 homes across 26 provinces in Vietnam.
Floodwaters in Vietnam are receding, draining through the Red River -- the main watercourse in the area -- into the sea.
Authorities in several districts in the Red River delta ordered more than 50,000 people to evacuate their homes as a precaution while the runoff passes through.
Communications cut off
The floods have devastated more than 250,000 hectares of crops and huge numbers of livestock, Vietnam's agriculture ministry said, with farmland around Hanoi hit hard.
In the deadliest single incident, a landslide in Lao Cai province annihilated an entire village of 37 houses, killing at least 42 people with 53 still unaccounted for.
Rescue teams pulled victims from the mud on Thursday, carrying them on stretchers to makeshift shelters where neighbors and relatives carefully washed the bodies in readiness for burial.
Survivors picked through the mud and wreckage to retrieve what family heirlooms and possessions they could find.
Fifteen bodies have been recovered in Cao Bang Province after a landslide on Monday pushed a bus, along with several cars and motorbikes, into a stream, state media said Thursday.
Myanmar camps
Myanmar's junta government has set up around 50 camps to help people affected by the floods, Lay Shwe Zin Oo, director of the social welfare, relief and resettlement ministry told AFP.
The Global New Light of Myanmar, the state-run newspaper, said train services on the main line between Yangon and Mandalay were suspended because some sections were flooded.
The Mekong River Commission, the international body overseeing the crucial waterway, issued a flood warning on Thursday for the historic Laotian city of Luang Prabang.
The Mekong is expected to hit flood levels in the coming days in Luang Prabang, a UNESCO world heritage site, the commission said in a bulletin.
In Thailand the death toll has risen to nine, the Department of Disaster Prevention and Mitigation said, including six killed in landslides in Chiang Mai province.
All flights were suspended in and out of the airport in Chiang Rai, some 145 kilometers (90 miles) northeast of Chiang Mai, aviation authorities said.
Further north, Mae Sai district on the border with Myanmar is suffering its worst floods in 80 years, Suttipong Juljarern, a senior interior ministry official said in a statement.
The Jet Ski Association of Thailand has sent 16 jet skis to help with relief efforts, Dechnarong Suticharnbancha, the body's president told AFP.
Some of the currents in the floodwaters are too strong for normal boats but jet skis are able to navigate them because of their powerful engines.
A video showing champion jet skier Kasidit Teeraprateep rescuing an old woman from a torrent of murky water circulated on Thai social media.
Heavy monsoon rains lash Southeast Asia every year, but human-made climate change is causing more intense weather patterns that can make destructive floods more likely.
Climate change is causing typhoons to form closer to the coast, intensify faster and stay longer over land, according to a study published in July.
VnExpress has launched the campaign "To Weather the Storm" to help communities recover and rebuild livelihoods after typhoon Yagi. Click here to lend your support.