I both ran Track & Field in HS way back 00-03 and then coached as well from 14-19.When I ran sports programs in the Chicago 'burbs, we started softball with daylight savings time. Back then DST started the first week of April, and we sometimes had cold but never had snow. What we did have was full onslaught thaw; the fields could be muddy as all Hell into May. Sloppy muddy conditions would be what I would be concerned about.
I bring this up because, here in Toledo at a very similar latitude to Chicago, it made the regularity of snow in April glaringly obvious to me. Because our seasons always started with the first weekend in April. And every season I can recall there was one meet where driving snow was a problem. Every time. Its crazy surprising to me that you never had an early April snowfall in Chicago. I suppose its far enough away for weather patterns to be different, but it doesn't FEEL like it is.