DENVER - Until now, Denver has only had 18 snowless Octobers in over 130 years of data. Of those, 2 seasons ended with above average snowfall.
Further, this is only the 13th year since 1882 with no snow in September AND October. Of those 12 prior years, only one ended with above average snowfall. That single season, 1950-51, was actually in a La Nina pattern.
Why do I point that, La Nina, out? I do so because there are a lot of misconceptions about El Nino and our Colorado and Denver winters. As a reminder from my previous writings, El Nino patterns have brought Denver an average of 59" of snowfall versus 58" as the Neutral pattern average and 53" as the La Nina average. That's the difference of a single snow storm, and hardly an incredible snowy advantage to be in an El Nino pattern. That's the breakdown of seasons as a whole.
As far as our largest snow storms, more than half of Denver's biggest came in Neutral years, 9 in El Nino years, and 4 in La Nina Years. Remember, there's no such thing as an El Nino snow storm or a La Nina storm. El Nino and La Nina are longer term fluctuations in precipitation and temperatures, not singular events.
We certainly could have a large snow storm or two or three...this season. And there is still a chance, albeit dropping steadily, that we end the season with above average snowfall. Yet, based on history only 1 of 12, or 8%, of those years without September and October snow ended with more than average (57”) snowfall. Of course, that is a historical perspective and we all know that weather does not exactly repeat itself twice.
It seems appropriate to add, although maybe obvious, that Denver is already well past the average first date of measurable snowfall, which is October 19th. The city has had a number of late first snows the past several years: 11 November 2014 (season ended right at average. Note that snow fell, but wasn't measured before this date), 15 November 2010 (season ended 34” below average), and 14 November 2008 (season ended 14” below average). The latest ever date of first snowfall is 21 November 1934, and that year ended within 9” of being average.