Hello,

you subtract the surface sea level pressure of the Novembers before the 10 mildest Decembers (January / February months) from the Novembers before the 10 coldest Decembers (January / February months) since 1987. You get the areas of the greatest differences between the two groups, what you can see below are the charts leading to a cold month, just the opposite leads to a mild month in the east of Canada (defined as 45 – 60°N 95 – 50°W).

Novembers before cold / mild December:

Novembers before cold / mild January:

Novembers before cold / mild February:

Yours

KHB