sioux falls, sd
Many east of the James River Valley experienced a hard freeze Sunday morning as temperatures dipped into the 20s. Sioux Falls fell to 27 degrees that morning.
A Facebook post on our KELOLAND Weather page mentioned, "After a hard freeze, expect snow six weeks after." So I looked into such a possibility.
Scanning the archives since 1990, I looked for the first hard freeze in the fall counted six weeks after and looked for any measurable snow. Here's what I found.
It snowed exactly six weeks after a hard freeze three times since 1990, or 14 percent of the time. The average of those three times was just over three and a half inches.
One of the most infamous blizzards in Sioux Falls happened six weeks after a hard freeze. It was the Halloween blizzard of 1991. Six weeks prior to Halloween, the thermometer fell to 27 degrees on September 19.
Within a window of one to five days, the percentage jumps to 55 percent of the time, with an average just over four inches.
Of those 15 years when it snowed close to six weeks after the hard freeze, the amount of snow stayed at an inch or less 11 times.
With the hard freeze in Sioux Falls on Sunday, September 23, expect snow to fly November 4, give or take a couple of days.