Looking back at more than 135 years of local weather data, Chicago has experienced its first measurable snow as early as October 12 (in 2006) and as late as December 20 (in 2012). That’s why Nov. 17 is the date of the average first significant snowfall in Chicago. Remember, measurable snowfall is one-tenth of an inch or more on the ground, while anything less is considered a trace amount. The chart below shows the date of the first measurable snowfall for each year since 1885. Amounts are available, by year, beginning in 1905.
