Tuesday night's trace amount of snowfall wasn't the earliest occurence of the white stuff in Champaign-Urbana.
State Climatologist Jim Angel said of the seven years on record where C-U saw snow in October, the earliest occurrence came on October 9th, 1925, when a trace amount fell, similar to last Tuesday night. Angel said the earliest measurable snowfall in C-U was on October 30th, 1993. He said that instance was the last time we saw snow in October before Tuesday night.
Angel said there's no formula to predict whether snow will fall earlier than normal. Rather, he called it the luck of the draw in getting the right weather conditions at the right time.