When does Chicago's first inch of snow come?


More weather whiplash this week as we go from snow to 70s. The first flakes of the season flew on Monday as O'Hare picked up a trace of snow. It was the earliest first observed snow of the season since Oct. 4, 2014. The average first date for a trace of snow is October 31, so Monday's snow was about a month ahead of schedule.

The week started out feeling like late November and by this weekend it will seem more like the middle of September. Highs Saturday and Sunday will be around 15 degrees above average.

It was cold enough for snow Wednesday morning as lows dropped into the 20s well west of the city. Aurora was the cold spot with a low of 24 degrees. Woodstock and DeKalb both dropped to 28 degrees. O'Hare officially dropped to 33 degrees. The National Weather Service pointed out on that some states in the deep south were even colder than Chicago Wednesday morning.

No sign of any more snow at least through early next week. After our warm-up this weekend it looks like the next shot of air cold enough to possibly produce snow doesn't arrive until the end of next week. One computer model is suggesting enough of a chill at times from next Wednesday through next Friday to support snow. Moisture looks very limited from today's vantage point so other than some flurries, it doesn't appear like significant snow would fall next week.

When do we typically see enough snow to really matter?  The first measurable snow (.01 inches or more) on average falls November 18. It has come as early as October 12 (2006) and as late as December 28 (last year).

The average date of the first inch or more of snow piling up is December 7. It has come as early as October 19 (1989) and as late as January 25 (2013).

We would typically see our first .01 inch of snow or more in about a month from today and our first inch or more in about seven weeks.

Snow lovers just need to be patient. The early winter forecast is calling for more snow than average. I will post an updated and final winter forecast in just a few weeks.