In my area that would be when rain water coming in, or a drain is clogged. It might not be clogged just handling to much water....Des Moines Iowa’s went under water in 1993, had to use a sump pump to dewater the basement .
Two things. If you have a sump pump the drains empty into the pump has failed. If there is no sump pump and the drains empty directly into the sewer line it is clogged.
Where is it backing up from? I would a plumber (licensed) out asap.
If it coming through the walls, the waterproofing has failed.
Main sewer line is clogged and needs clean out. If you've had heavy rains, it could be seeping up through the concrete floor if unsealed, or the walls are in poor condition. You've got a leaky pipe in the basement or the water is traveling from somewhere in the wall.