In the southern Midwest and in a few of the arid states, there are areas where flash flooding is a problem. In a heavy rainstorm, the shape of the watershed is such that most of the water shows up at a river or stream bed as a concentrated pulse. That can be particularly dangerous in a seasonal stream bed, because you are more likely to have people in a dry stream bed than a wet one. Of course you also have the problem of people crossing a dry bed and not being able to cross back until the rains stop.

There are some famous videos of people getting caught by flash floods in the Middle East as well. The return of the rains seems to have become a spectator sport and people get too close.