Officials say flooding and resulting strong currents in waterways are the main causes for the increase.
The Missouri State Highway Patrol said as of Thursday, 30 drownings were reported in the state, compared with 29 in 2014.
Patrol spokesman Captain John Hotz said some of the drownings occurred when people tried to drive through flooded roadways and were trapped or swept away.
The Joplin Globe reported high water and strong currents also cause problems with hidden underwater debris and re-circulating currents, and strong undercurrents near low-head dams.
Other dangers include being pinned in an overturned boat or canoe by the strong currents.