After a slow start, the second half of October recorded several snow events that greatly expanded the snow cover over Siberia. Some studies have suggested that October snow cover has some correlation with winter temperatures in the United States, especially areas east of the Rocky Mountains. In October the snow cover can increase anywhere from between 4 to 6 million square miles, an area larger than the United States.
Last year Siberia recorded below average snow cover during the month of October. This year, there has been a significant increase in snow cover and last month ranked as the 11th highest total in the past 45 years. The theory is that the larger the build up of snow in Siberia early in the season, the higher the likelihood that large Arctic air masses will form and eventually move into North America, especially in January and February bringing a colder than average winter.
Of course, this is just one of many possible drivers that could influence the weather patterns during our cold season