As far as snow chances, not saying there will be no negative marine influence for South Bend, but I would think they are far enough inland to not get completely skunked like the areas near the IN/southwest MI shore probably will. So I dug into October snowfall climo for SBN.
There have been exactly 2 years that produced an inch or more of snow on October 18 or earlier -- 1.5" on 10/18/1972 and an incredible 13.0" on 10/10-11/1906, which appears to have been a lake effect event (in case anyone is wondering, the storm in 1989 happened just after the 18th).
I found an alleged 1.0" snowfall in September 1994, but this appears to me to be erroneous as the lowest temp that day was 41. Maybe it was hail or something? Anyway, this was disregarded.
So, if they can somehow manage to get an inch, it would be pretty significant. Really anything measurable at all would be noteworthy for this part of October.