I had asked the IowaWX Blog’s Mysterious Meterologist about this topic as there has been numerous searches for this topic along with the first frost. They sent two maps that were produced by the NWS in Des Moines for when the first measureable snow and the first 1 inch snowfall usually occur. Now given that today it was in the 60s and 70s and no snow is in the forecast in the next two weeks but given the wild weather of the past in October (see the post about the Blizzard of 1997 that occurred in late October), I thought this would be a good time to post this now.

As you can see from this map, the first measureable snow means any amount over a tenth of an inch of snow. Places in the Northern part of the state see their first measureable snow by November 10th. Sioux City, Spencer, Mason City and Charles City by Mid November. Omaha/Council Bluffs, Fort Dodge, Waterloo and Decorah by November 20th. Shenandoah, Des Moines, Ames, Marshalltown and Cedar Rapids by the 25th of November, and most of the rest of the state by the end of November except extreme southern Iowa and along the Mississippi River from Dubuque to Davenport.

The first one inch snowfall usually occurs not long after the first measureable snowfall. By Mid November, the Siouxland and Iowa Lakes Region has usually had their first 1 inch snowfall, by November 20th, that area expands to include the Omaha/Council Bluffs metro area. Around November 25th, cities that have usually recieved their first 1 inch snow include, Carroll, Mason City and Decorah. On the first of December, the beginning of meterological winter, the first 1 inch snow has usually occurred in the Northwest 2/3rds of the state. Cities that usually do not recieve their first 1 inch snowfall until December include Cedar Rapids, Dubuque, Iowa City, the Quad Cities, Ottumwa and Burlington.

Remember this does not mean it won’t snow until these dates, it can snow in October or it my not snow until Christmas, these are just averages since 1950.