Most victims were drowned but others were killed by landslides, snake bites and lightning strikes, officials say.
The death toll from monsoon storms in Bangladesh rose above 100 on Friday with flood levels still rising in many parts of the country, officials said.
About 20 people have died in 48 hours, taking the toll to 104, making it one of the worst monsoons in years, officials said. Most victims have drowned, but some have been killed by landslides, snake bites and lightning strikes.
Five girls drowned when their boat capsized in a flood torrent in the northern district of Jamalpur on Thursday, district administrator Ahmed Kabir said. The youngest among them was aged six.
The Brahmaputra river, which flows out of the Himalayas, has risen dramatically since July 10, leaving 1.2 million people in Jamalpur without homes or affected by the floods.
The river last week was at its highest level since authorities started keeping records in 1975.
Six villages in Mymensingh district were flooded after waters breached an embankment and forced 2,000 people to flee their homes, district administrator Mizanur Rahman said.
Officials say five million people have been affected by the floods since July 10. Several hundred thousand have been forced out of their homes.
The state-run Flood Forecasting and Warning Centre said at least 26 of the country's 64 districts, covering a third of the country, have been flooded by heavy monsoon rains and a deluge from Himalayan rivers in India and Nepal.
The centre said floods would remain high in many districts until Saturday.
Bangladesh is regularly flooded around June to September due to monsoon rains.