Trends in the dates of the earliest and latest snowfall
Is winter starting earlier and ending later than before? Many people think so thanks to snowfalls in recent years that start in October/November and the March/April snows that delay the onset of spring. Below are graphs showing the dates of the earliest and latest snowfalls of 1" or more for Huron SD, Sioux Falls SD, and Le Mars IA from the late 1800’s through 2006. The running 10-year average of these dates is also plotted, along with a trend line of the 10-year average to show how these dates have changed in the past 100+ years.
From the above graphic, you can see that the trend in the earliest snowfall of 1" or more at Huron shows a trend of being about 2 weeks earlier, going from around 11/25 to around 11/10.
From this graphic, you can see that the trend for the average date of the latest snowfall at Huron is about 1 week later, going from around 3/27 to 4/2.
This graphic of the earliest snowfall at Sioux Falls also shows a trend of being about 2 weeks earlier, going from around 11/27 to around 11/12.
For the latest snowfall at Sioux Falls, the trend shows it coming about 1 week later, going from around 3/20 to around 3/28.
For Le Mars, the above graphic shows that the earliest snowfall of 1" or more has trended about 1 week earlier, going from around 11/26 to around 11/18.
For the latest snowfall at Le Mars, the trend is for it to be about 1 week earlier, going from around 3/26 to around 3/18.
Based on this data and these graphics, it does appear that there is a trend for the first snowfall to come earlier in the season by 1 to 2 weeks. Also, for Huron and Sioux Falls, the trend is for the last snowfall to come about 2 weeks later into Spring. Will these trends continue into the future? Stay tuned to the unpredictable weather of the Northern Plains for the answer. We may know more in another 100 years!Return to News Archive