Just last week in Illinois there was a bunch of roads the were closed because of flooding. The officer claimed that I "hit" a road closed sign, but all I did was run over it even though I didn't see it because the wind blew it over, and it was pitch black out he gave me a ticket for failure to reduce speed to avoid an accident, is it my fault

Yes... its your fault... you are required to reduce your speed in inclimate conditions. To avoid hitting cars people and other things.

Failure to reduce speed and too fast for conditions are effectively the same charge. Because it could have just as easily been a person walking because their car broke down.. etc...