Our September cold snap could lead to prolonged cold this winter.
Since 1990, Sioux Falls temperatures have dipped into the 20s just five times in September. The following Octobers were close to average.
But it's a little more interesting when you look at the Novembers that followed. Two of those years, temperatures were well above average with average highs in the 50s and 60s. But those were during La Nina years.
The remaining three Novembers were much cooler with average highs in the 30s. This in turn allowed for an average, just under seven inches of snow. Those three Novembers were during El Nino or neutral years.
We are currently in a neutral period with a slow trend toward El Nino. This could be a sign that this November will be cold and October will be average.