Castle Rock’s First Snowfall and Freeze Could Be Coming Soon!

With the heat the front range is experiencing this week, it’s hard to imagine that fall is right around the corner and with it cooler weather, freezing temperatures and yes… even snow! The month of October is now only 10 days away and that’s important because it is one of our major season transition months in Colorado. I’ve been looking at the data, specifically for the Castle Rock area lately and have found some interesting statistics:

Data from NOAA

Source for data:  NOAA


For the past 10 years, all of our first measurable snowfall’s (an amount of 0.1 inch or more) have occurred in October or November. The majority of our first snowfall events occur in October with 7 of the past 10 years holding true to that trend. Looking at only the past 10 years seems hardly statistically significant so I decided to dig a bit deeper.

Looking back at data for the past 61 years 37 of those years featured our first snowfall in October. This means that for the past 61 years, we had our first measurable snowfall in October 60% of the time. Not a huge number as our weather can be drastically variable from year to year, but 60% is a pretty high average overall in the world of weather.


The National Weather Service classifies a first freeze as the day when a temperature below 32 degrees Fahrenheit is recorded. The tricky part is that due to Castle Rock’s higher altitude and more varied terrain, we often experience our first freeze before Denver. In the past 10 years, all of our freezes have come in October and usually within the first half of the month. We had one instance of a particularly cold in 2006 where our first freeze came in September instead.

Castle Rock CO snow stats

Source for data: NOAA

So despite all the warm and dry weather we are experiencing this week, keep in mind it can all change very quickly. Fall in Colorado is a season that features huge temperature swings from day to day in what I like to call our “Weather Roller-coaster.” Given this year’s larger scale atmospheric setup, I would not be surprised to see some snowfall in the middle to second half of the month.

We’ll keep an eye on the outlooks and models as we get into October and pass along any information on when our first taste of snow may be!

John R. Braddock
Storm Chaser/ Amateur Meteorologist at Mountain Wave Weather
John R. Braddock is a NOAA/NWS Certified Storm Chaser and Amateur Meteorologist living in Castle Rock, Colorado. A graduate of Colorado State University with a Bachelor's in Computer Science and a Colorado native, he specializes in short range forecasting, severe weather and mountain weather dynamics.


    • Brian on September 20, 2016 at 9:32 am
    • Reply

    you are missing 2015!!

    1. Quite correct, thanks for the heads up! I got the data from NOAA and apparently they don’t have 2015 for some reason! In fact I couldn’t find the data anywhere from them so I had to go to my own records. Our first snowfall last year was in November, we ended up with 16.2 inches of snow for the month of November which was way, way above average!

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