If the river blows, most of the river will be unfishable and visibility will be poor so only snaggers will catch fish.
It is however good for moving fish. Not good for existing redds as they may get washed out.
Also potential for flooding and property damage so instead of fishing a lot of people will be putting up sand bags and dykes to protect their homes.
This is really the extreme.
That's not to say that people can't catch fish if they know how.
My favourite is the slow steady rain, just enough to cloud the surface of the water and cool it down.